The whole idea behind CoD being a "gamechanger" is that it's a 1:1 port of Black Ops 2, but I think it would actually sell better if it was an original game. Of course, for it to sell at all we have to assume that Vita will have a healthy ecosystem when the game releases and that said game isn't complete shit.

if this will be a multiplatform then i don't see people buying it on Vita as FPS games are better suited for the big screen. people will most likely buy it for PS360 rather than buy it for the Vita unless it is exclusive but I'm sure people before me have already said this

2 million max I'd say.

1.5-2million. Being unable to play multiplayer everywhere will stop it from being a true mega hit, because it's multiplayer that sells CoD. If that was possible then it could multiply by anything up to a factor of four.