Yeah, it'll never happen.... but we can dream
I think Rich would KO Hughes. Trigg had Hughes rocked, and I think Rich's punches are a lot more devastating than that. Look at the Nate Quarry KO, or Loiseau's face after five rounds.
I do agree, though, Hughes ground game is better than Franklin's. If I were Hughes in that fight, I would probably try to stay on the inside and bring things to the ground (to state the obvious, I guess).
Matt Hughes vs. GSP? I see GSP winning by KO or ref stoppage (punches). I mention this, because I think Hughes vs. GSP would probably be similar in some ways to how Hughes vs Franklin would go down.