I'd rather see two HWs and two LHWs go to SF than see Gegard and Fedor go to the UFC.
The only way I could believe this is if DW decides a "Liddell/Wanderlei" type co-promotion is finally worth it. Co-promote just once - maybe on SF's CBS deal. But it'd likely be a PPV.
Spike would win because they get to go on CBS and take half the bank of an easy 100$ PPV, SF would get more exposure, Fedor and Gegard would make mad bank and "prove" themselves.
Also some UFC clowns would get spanked.