The idea that there are raptor riders on the way had me thinking of saurian possibilities lately, particularly that there are no good ranges for clearly 25/28mm scaled dinosaurs out there.
I reckon you could fit the pieces for a nice mid-size carnivore, like a largish Ceratosaurus, or a smallish Allosaurus and/or a Megalosaurid or smaller Tyrannosaurid on a WGA frame, but then I have none of the skills relavent to actually making an informed observation about that. ;) But at least these animals have similar enough body plans that they really just need a head and arm swap to give multiple species.
To me it's hard to tell how much extra space might be left on a sprue after you break up and split things in half (but maybe not everything needs to be split in half, like they do on GW kits? But any extra sapce could be used to give alternative heads and arms/hands. (or really, just alternative upper jaws, as the lower jaws for alot of these animals when at the same size is going to be similar to the point of just being able to re-use the same piece.
I'd love to see some bigger species represented as well - but the larger carnivores begin to have very divergent body types (T-Rex and Giganotosaurus for example seem similar enough from the side, but head on they are very different, with the Rex being much, much more robust - tales of its demise to either Gianotosaurus or Spinosaurus are unlikelly to be true. But we may never know for sure until we have such kits in hand and can experiment for outselves ;))