Penn/Pulver are out of the question since they are preparing to fight each other and won't risk injury. Sherk/Franca are slated to face each other also so that takes them out of the mix. Nick Diaz is suspended, (I don't know if his suspension is valid in Japan though it would be safe to assume it is) Fitch would be a good candidate, I would like to see some 155lbers though, maybe Roger Huerta,Tyson Griffin,Frankie Edgar, Joe Stevenson, or Spencer Fisher. (although I don't see any of the people I just named making it very far into the tournament)
With Serra/Hughes tentatively scheduled in August, I doubt Matt will be in the GP.