think about it this way:
sony is selling final fantasy 7 on PSN exclusively right now. there's no way that microsoft can ever have that title on XBL, unless sony decides to sell it to them. sony published the game all the way back in the ps1 era. that makes them the de-facto owners of the title.
then again, no amount of money would ever make sony sell their priceless gem to their hottest competitor, unless microsoft had enough money to buy out the whole of sony corp.
and that will never happen. sony corp is far too big and far too smart to do such a foolish move. also, microsoft wouldn't throw away that kind of money on any single game.
so since sony owns the rights to the name, game, and storyline, and neither sony nor microsoft are stupid to fight over this one game that clearly cannot be made on any other console apart from one made by sony, this thread is quite pointless.
EDIT: think of it like this also:
it's like.. Halo 3 receiving a port to the PS3. microsoft has publishing rights to halo 3, and therefore owns halo 3 unless they sell it to sony and allow them to make the port. otherwise it's impossible.
of course, none of this can ever happen. to the people likening this to ff13, well, 13 was not published by sony. 7 was published by sony.