Soundwave on 01 September 2014
Making the game for PS3/360 as the lower baseline makes it easier to port to PS4/X1 ... 3DS to PS4/X1 is probably too much of a gap (too many things would have to give), that's probably why the 3DS isn't getting it. They likely figure RE is a home console centric franchise and the majority of the sales will be there.
