I'm looking forward to this fight, too. But I'll bet that will be one of the more boring fights. I see it going the distance, with Hughes being in Royce's guard most of the time. The crowd will get weary of the stalemates, and start booing every time it goes back to the ground. Hughes will get the decision based on the fact that he will be the aggressor while Royce will just be defending himself from the ground. I wouldn't be surprised if it is a duplicate of Royce vs Ken Shamrock, where it stayed on the ground almost the whole time, and was boring to watch.
Hughes will be much too physically fit to run out of gas. And he's too experienced to make a dumb mistake that Royce can use against him. Royce, on the other hand, has enough fighting experience to deal with Hughes stand-up game. And on the ground, Royce has enough experience and know-how to not get submitted by either strikes or submission.
So as I said before, it will go the distance, with Hughes winning unanimous decision because he will do better when they stand. And Royce will stick to putting Hughes in his guard and defending from there, which will lose him points in the judges eyes since Hughes will be seen as being more the aggressor.