I think the argument for PS4/X1 versions is that when/if either PS4 or X1 become standard transitioning into next gen, it will be easier for TOs to run USFIV alongside the new games coming out. I think that's a good argument. PS4/X1 versions would also make a bit more sense why the retail version is coming so much later.
Still think people's prayers are carrying them on this though.
When is that though? XRD is PS3/PS4, P4A2 is PS3/360, MKX is 360/PS3/XBO/PS4. No fighters are coming out on the current gen that isn't gonna be available on previous gens. Unless the previous gen runs worse to a degree that it becomes a hindrance to players then I don't see TOs switching to current gen for quite a while.