He aint fighting Barnett if he wins, would be stupid for the UFC if Barnett wins to put Big Foot against him cause if Foot wins you just killed the next contender after Werdum for a guy Cain already smashed twice.
More likely you do Big Foot vs JDS or Big Foot vs Stipe/Gonzaga winner, or Shaub, someone like that if Big Foot wins.
UFC def needs to have Barnett get a title shot after Werdum if he beats Happa. Cain needs all the big name challengers he can get and having 2014 fights with Werdum and Barnett would be good for Cain and the UFC.