They should do Bisping vs Silva. Been waiting for that fight for some time now. Bisping is well rounded and might be able to use his grappling ability against Silva, heck he was using it at times to push Sonnen around. His striking is decent as well although not on the same level as Silva's.
It would also be a pretty big fight as both Silva and Bisping are well known and followed fighters.
Then the winner of Weidman vs Boetsch could have the next shot depending on how that fight goes.