I'm a JDS fan, but I particularly don't care if he gets a rematch after 1 fight. While I do think he can beat Cain in a third fight, and there's no taking away from what he did in the first match, Cain's latest win was essentially five rounds of him dominating the fight. If you look at it from the UFC's perspective it's a bit easier to promote a rematch for a fight that didn't make it past the first round because you have the angle of "He just got caught," to fall back on, rather than 25 minutes of almost complete control.
With that said the HW division has always been the thinnest in the UFC's roster. I'm not sure where they're going to take it from here, but I think we should at least see how some other key matches play out before we jump to immediate rematch. It's obvious that if both fighters win their next couple fights they'll meet again though.