You see, having taken a look at the official UEFA site, it would seem Sony (and indeed the PlayStation brand) is just one of the sponsorship partners of the UEFA Champions League competition, which would guarantee it placement on anything to do with the event and that includes Xbox 360 games.
Seems obvious they will stay in. With so many soccer games on the market they are basically just a medium for the commercial sponsors (Toyota Fast Break in NBA 2k anyone). There is 0 need for a Champions League game. Even if they have fixed the gameplay issues from FIFA 07 that's what patches are for. This game is squarely aimed at the European market. They are trying to bring them the whole Champions League experience. Well in reality the only thing that differentiates the Champions League experience from any ole game is the sponsors. I play 10-20 hours a week of FIFA 07 and I will not buy this game on principle.
Don't think of it as a PS3 add on your 360. Think of it as a PS3 ad on your TV.