Going by some of the posts I've been reading on various forums it seems even today people seem to think new software should run on a A500! 
We aren't going to change the world of gaming at this point, unlike in the 80's when the amiga had more colors, and better sound than anything out there. So right now, yeah new software that can run on anything from an a1000 to a minimig etc. would be a good thing.
Or you could go the opposite direction and require an akiko chip (cd32) or an ec version 68020 or crash on anything else or some obscure rtg version.