From my armchair, it seems like we haven't really seen an old-fashioned war between large, evenly-matched armies in a very, very long time.
Illustration: The Ukrainian Foreign Legion, one possible face of the modern asymmetrical fighting force.
Seems like just about all of the war in my lifetime has been an asymmetrical matter of large first-world coalitions throwing the weight of technologically-advanced military hardware at small armies and major infrastructure, which quickly devolves into urban and guerilla warfare against crudely-equipped fighters who are all but indistinguishable from civilians.
Illustration: This is just an exercise: dystopian militarized police force on a typical modern "peacetime" battlefield in Everytown, USA
It seems like much of the world is marching grimly toward a dystopian situation where militarized police forces withdraw from the public to provide security for the powerful, the wealthy, and the privileged, while warlords and private criminal gang armies war against each other, and the public. Police forces sometimes seem almost indistinguishable from military contractors, and are more likely to be deployed against increasingly frustrated and dissatisfied civilian populations than violent criminals. Cameras and smart phones are more common and powerful weapons of war in many of these paramilitary conflicts than tanks and jets, while "less lethal" weapons like rubber bullets, bean bags, tear gas, batons, microwave and sonic weapons, flashbangs, and the like have become increasingly ambiguous in their short-lived role as a Public Relations-friendly crowd-control alternative to overt lethal violence.
First-world militaries seem to be increasingly drifting away from the human element, towards drones, smart weapons, and robots. Casualties play poorly to the public when it comes to maintaining public support for war in democratic countries, making these robotic alternatives desirable, but "collateral damage" from these weapons also results in public relations disasters when civilian bystanders become accidental targets, and aritifical intelligence and remote control can get alarmingly sloppy.
Illustration: the (for now) non-threatening future of urban pacification.
Police forces are already deploying robot "police officers" - they don't look like much now, and at least one of the examples I've seen was designed to look cute and friendly: it simply rolls up and down streets with a painted cartoon smile on its bland robot face, warning pedestrians not to litter, and answering simple questions about where to find local points of interest, and serving as a public option for pedestrians who need help to call for emergency service. Drones are also in common use with modern police forces for many of the same purposes that they are in modern military forces: they can provide a better picture of the "battlefield", provide intel on enemies, etc. I've also seen prototypes of weaponized robots for crowd control, or first contact with dangerous criminals, etc.: robotic "police dogs" with mounted less-than-lethal and lethal weapons. It will be just a matter of time before it becomes routine for police to send armed robots in to raid the hideouts of dangerous criminals, or to put down civilian riots and acts of civil disobedience with weapons representing a range of possible lethality. Among the dystopian benefits of robot police and soldiers is that they do not feel conflicted about orders that violate human rights, or feel sympathy for human targets, while robots are also more disposable and replaceable than human officers.
Illustration: The less friendly face of the modern police robot - a sort of armed "robot police dog". How long until its counterparts find their way into the hands of equally militarized criminal gangs, militias, cults, etc.?
And it's not just a militarized police force and criminal gangs that can make urban city streets look like a bizarre dystopian war zone - civil unrest can trigger a military response as well, as civilian populations rise up against out-of-touch, careless, and abusive governments, or nations even break down into revolution and civil war. I worked in Baltimore through the Freddie Gray riots in 2015 - nothing quite drove home the gritty, militarized, cyberpunk dystopia of the 21st century quite like seeing armed national guardsmen and military vehicles posted on the streets of the "Charm City" while tourists and business-men in designer suits and ties go about their every-day Fortune 500 big business while conducting business by smart phones and Bluetooth, and clouds of black smoke from active inner-city rioting and looting of drug stores and police stations rises above the buildings only a few city blocks away.....
Illustration: Baltimore, USA, 2015... it could as easily be Kenosha WI 2019, or Washington DC in 2022, or Hometown, Idaho in 2035....
A lot of modern warfare seems to be fought on some really strange battlefields: cyberspace, mass media, social media, denial-of-service and hacking, propaganda and counter-propaganda, internet memes and late-night comedy routines, socio-political paradigms, thoughts and ideas, hearts and minds. Some of the world's most effective soldiers might look like a bunch of sedentary activists armed with energy drinks in a call-center boiler room full of smart phones and laptops targeted at banks, search engines, and lobbyists. Decisive counter-attacks have no doubt been fought by undercover agents dressed as janitors or plumbers or pizza delivery drivers springing surprise raids that are carefully scrubbed from the news cycle and buried under disinformation and more sensationalistic "fake news" distractions. The ultimate direction of modern wars may in many cases have been decided in these arenas before the first shots are fired on real battlefields, and entire governments might have been toppled by the results of warfare in these theaters.
Illustration: Cyberwarfare. "Gentlemen! You can't fight in here - this is the war room!"
The nuclear genie, with its cousins, the bio-weapon and chemical genies, are all but completely out of the bottle. Efforts to contain them have lasted about a century or so, and the threat they pose to large, ripe targets in wealthy, powerful world empires has been used to justify more than one invasion or "police action", but the world's policemen do not seem as confident as they used to, the technology needed to produce these weapons has become increasingly more affordable, and large military superpowers have grown careless, and in some cases have collapsed and become desperate. It's only a matter of time before these weapons become widely available to smaller militaries, and to paramilitary groups, who will begin using them against the powers that developed and used them first.
Illustration: A typical apocalyptic Chemsuit Goon seeking a doomsday scenario.
So, in addition to the great ideas from the replies before mine, I think a "20 Minutes Into the Future" cyberpunk-style today/tomorrow tabletop skirmish line should not neglect at least considering the following:
- Armed civilians resistance and other irregular forces, representing:
- guerillas
- militias
- cults
- gangs
- terror cells
- undercover agents and military advisors
- also doubles as hostages and bystanders (objectives or obstacles for skirmish gaming scenarios)
- Mercenaries/Private Security Contractors
- Special Forces, also:
- snipers
- scouts
- saboteurs
- the guys who tag targets with lasers etc. for laser-guided and smart munitions
- intelligence/counterintelligence agents
- Police:
- SWAT
- Crowd Control
- Security Guards
- Military Police
- Secret Police
- "NBC" (Nuclear, Biological, Chemical) weapons, chemsuits, decontamination stations, sealed infantry vehicles, etc. Faceless chemsuit goons tend to look look scary and intimidating, and have become a common sight in post-apocalyptic movies and video games for a reason.
- APCs, fighting vehicles, scout cars, armored cars.
- Heavy weapons such as RPGs, anti-tank guns, improvised explosives, mine-layers, etc. - both crew-served, and mounted on self-propelled robot chasses
- Robotic sentry-guns: a dystopian near-future favorite in Aliens, Half-Life, and many other movies and video games. Civilians under the implied threat of thoroughly inhuman robotic guns controlled by remote corporate overlords are perhaps a perfect defining image for the dystopian Cyberpunk genre.
- Security cameras and drones, surveillance vehicles. (Surveillance vehicles make another fine objective for cyberpunk style skirmish gaming.)
- "Robo-cops" - robot "dogs", police drones, etc. for "urban pacification" purposes. Remember that Robocop and Terminator both draw from the thoroughly cynical cyberpunk aesthetic, and that faceless robot machines used to "pacify" civilians and enemy combatants make for some great enemy combatants in a near-future skirmish game.
- Crowd-control vehicles - sonic/microwave weapons, water cannons, grenade launchers (can in this context be loaded with teargas, rubber batons, etc.)
- Computers, Coordination, Communications, Command and Control - vehicles and other support and services for drones, etc. (These make great objectives in skirmish style games!)
- Personal equipment for soldiers, police, security, civilians, terrorists and other characters: computers and hacking decks, "briefcase nukes", gas masks and riot gear (even for civilians), satellite phones, cell phones and video cameras, door-breaching equipment, less-than-lethal gear (tasers, tear gas guns, batons, etc.)
- Scenic items - sandbagged walls and weapon emplacements, fences and barricades, metal detectors and scanners, guard posts and observation posts....
For what it's worth, the IronCore "Eisenkern" faction (as mentioned above by @JTam was not at all a bad start on a near-future army - Wargames Atlantic produces the great infantry figures in futuristic battle armor. It's unclear (and maybe unlikely) whether Wargames Atlantic will produce the armored car / infantry vehicle or the robot dogs/mules that were also produced for this game but are currently out of print, but these would have worked excellently for a cyberpunk/near-future skirmish or other wargame. Hopefully these vehicles and robots, too, find their way into production again!
As for main battle tanks, I have a feeling that, even in a world of EMP weapons, Rods of God, stealth bombers, and Daisy Cutters, the battle tank will find its nich in large government arsenals for a long, long time to come - especially in a world where a well-funded military's enemies are far more likely to be disgruntled farmers, protesters, and criminal gangsters armed with brickbats, rifles and Molotov cocktails, than uniformed soldiers armed with the latest anti-tank weapons.....