I think Rua will be sparked out cold by Henderson, unless the ref jumps in early. Henderson probably is getting on in age, but I think he still has too much for Rua, especially ring intelligence and timing.
Shogun CAN win this fight, for sure, but I don't favor him to. Both have unbelieveable Chins but Rua has good power and Hendo has freakish power. While I won't be surprised either way, I think Hendo will win if he fights a proper fight. If he starts head hunting from the get-go he's in trouble because Shogun has better footwork and he's faster, but if he mixes in the shots, works in the clinch, and throws the overhand right behind a feinted shot/clinch attempt, he'll land it and with more power than Shogun can counter with. I'm definitely looking forward to it.
I'm pretty shocked at the number of people on this thread who seem to think that Hendo is the more powerful striker/more deadly finisher/stronger man. IMO, he is none of these things. Shogun has more firepower and is more lethal than Hendo is. Hendo may have a slightly better beard, but he's sure going to need it when going toe-to-toe with a naturally larger man who is simply a better striker than him - and I would argue has heavier hands. Hendo has a fight-ending punch, but the rest of his artillery doesn't match up to Shogun's.
There is a difference between more powerful and better. Henderson hits harder. Can Henderson survive a stand-up battle? It's doubtful. Rua will brutalize Henderson with leg kicks and superior hand speed. The only way Henderson can have any success standing, is if he is able to repeatedly clinch and do damage in the clinch, or maybe land something big on the break away. I'm just arguing against it being a surprise if Henderson wins by ko. Henderson can finish anyone if he clips them on the chin. If Henderson wobbles Rua, and gets side control or even half guard, Rua will be in for a real battering if the cobwebs are there when Hendo gets into position.