DX is going to be a face group for now. Nitro and Melina are natural heels. No need to force the issue. DX should just be Triple H and HBK for now. It sucks that MNM had to break up, but this time it wasn't really the WWE's choice. Melina and Nitro have been getting heat backstage for a while now, and Mercury wanted out. Nitro and Melina were lucky the didn't get suspended. Look for Mercury to possibly end up in ECW.
I agree about the tag team division though. What's the point of even having 2 sets of belts? There isn't enough teams to compete for one of those titles.
I'm looking at the roster on WWE.com and I see all of these tag teams broken up into gimmickless singles competitors. It makes no sense to me. Why break up the Bashams, Cade and Murdoch, La Resistance, etc.... and then do nothing with the wrestlers? There are a few teams left like Brian Kendrick and Paul London, Kid Kash and Jamie Noble, Gymini, the FBI(Going to ECW), and of course the Spirit Squad. But there is no tag team division and that's sad. That's what the WWE gets for letting the writers book matches and having absolutely no game plan for anyone's future.