It is an interesting question, especially considering the Xbox 360 went through a period, beginning around the time of the release of the original Kinect onwards, where they weren't really putting out much in the way of new IPs or frankly even terribly varied ones. With the exception of a few exclusives that were ported in from PC, the majority of the 360's non-Kinect-required exclusives revolved around Halo, Gears, Forza and Fable, for a good few years. It may have been because they had all but guaranteed that the 360 had US sales dominance, and had no aspirations to try and secure a lead in the other territories, so they stopped experimenting with new properties and just stuck to the most profitable IPs they had. (except for, again, the original Kinect, cause Jebas there was a lotta stuff coming out for that.)
Either way, it's probably what has contributed to the concern some might have as to the variety of Microsoft's exclusive offerings going forward. But to answer this question, if I had to pick a property that might become another heavy hitter, I'd have to guess Crackdown. I very much enjoyed the first one, and it has that kind of mindless fun element that could make it extremely popular, if enough effort and resources are placed into its development.
Zanten, Doer Of The Things
Unless He Forgets In Which Case Zanten, Forgetter Of The Things
Or He Procrascinates, In Which Case Zanten, Doer Of The Things Later
Or It Involves Moving Furniture, in Which Case Zanten, F*** You.
