No one's really talked about it, but MvC2 was a ps2 game, right? Knowing Sony, they will do as everyone above has speculated and lay off the universal ps2 software emulation until ps2 hardware sales have declined enough, but there's a chance select games can be brought over before then.
Don't get your hopes up, even the ps1 releases have been 'slow' and that should basically be almost as easy as ripping the iso and putting it in the store. (I know, there's other things going on behind the scene, but in theory...)