Its kind of impossible to tell right now, anything can happen in a year. If I had said one year ago that Arlovski would be close to the HW title soon then you all would have called me crazy.
Right now we have:
Henderson/Belfort 3
Bisping/Whittaker
Mousasi/Hall
Give it some time, wait for some more high profile matchups to unfold and we'll have a better idea.