So are you saying that the PS3 owners dont own any games on their PS3?
Because migrating from PS2 is unimportant there, PS3 owners own PS3 games, so the graphics have to look comparable to what games they have on their PS3 system.
Dunno if you get my point, but my point is that its completely irrelevant if they have migrated from the PS2. The graphical impression of bioshock will not get any better because of that. PS3 owners play PS3 games! Thus, if bioshock PS3 doesn't look particularly good compared to current PS3 games, nobody is going to be impressed, even if they had a PS2 before, they aren't going to have visual expectations of seing PS2 level graphics, they expect PS3 graphics.