If the 360 can handle it, they'd be missing an opportunity. Of course if they make it for the 360 and there's frame dropping or constant loading, well, then they're making a mistake.
From what I heard, Square-Enix developed FF13 to make it like FF7 and FF8 to where you couldn't go back to certain places after you finished a disc. This is because the limitations of the size of the DVD all the places can't fit on a single disc. So unfortunately, these limitations are added to the PS3 version. Not only that but dual audio as well, which I'm not a fan of , but I hear a lot of Japanophiles complain about it.

So while the 360 could possibly handle everything the PS3 can and vice versa. The format limitation is the only thing that is holding the 360 back and unfortunately the PS3 too when a company has to downgrade a game on the system to work properly for both systems.