Even though this game still have around 2 and a half months left before its expected release, Capcom have already confirmed a pair of DLC characters, that will be available just weeks after the games launches (Or straight away if europe gets the collectors edition thats been announced in america)
Also, last year, barely a month after the release of Resident Evil 5, capcom released DLC for a versus mode. Of course, Versus mode itself was already in the game, you just needed to pay £4-5 pounds extra if you wanted to play it.
I think its highly likely that the DLC characters announced are already going to be in the game, you'll just be expected to pay ontop of the price of the game to get FULL access to whats on there.
Now, I know other companies are guilty of this too, but Capcom are just so blunt about it, and dont really seem to care.