I don't think this is likely though, I don't think Bungie would want to continue the exclusivity because it only hurts them. This was payed for by PlayStation to push units, hence why the advertising appeared you had to have a PlayStation. After the one year time frame of minimal exclusive stuff, it gets patched to xbox as well. Then the "comet" pack gets released which i can only imagine would be something large enough to call game altering, with more DLC to go with that for the next year until D2 gets released.