Ok I've only read the first page of this thread so I think I'm the first to suggest this but... Drew McIntyre. He gets all this special treatment from Vince and has been fired/suspended more than once on Smackdown, I wouldn't put it past them having him get fired again and then show up on Raw as the GM. Everyone will shit on it, but it would make storyline sense and would fit the bill of "last one you'd expect".
I think the role is too big to go to Bryan Danielson. I'm very shocked he's had big chants since he got fired as I figured only the IWC would know he was gone. I didn't think he'd gotten over with the casual fans enough for them to care if he was fired. He hasn't really proven himself yet in the WWE (Don't worry, I think he's one of the best in the world, relax), not to the degree that Wade Barrett has, and to come back from being fired to appease sponsors to having such a prominent role in the company seems a little much. I think when he returns he'll have to start from the bottom and quietly work his way up to avoid media backlash.
Michael Cole is the most obvious choice to me, given that he was exempt from the NXT beat down, was so involved with NXT season 1, gets hated on by the fans and has in the past been made fun of by almost every wrestler and announcer, and the e-mails from the GM are coming straight to him to be relayed to. Now, sure, Vince was on the phone to the new GM while Cole was presumably at the commentary table, but that could easily have been staged between the two. It just seems a bit too convenient, but knowing the WWE, because it's obvious they'll make sure it's anyone but Cole.
Triple H gets tossed around because he's taking time off and is always the evil mastermind, and an eternal leader of factions. This time however I think it would be pointless. These NXT guys need a leader who is either a non-wrestler or someone who won't overshadow them, and Triple H is waaaaaay above them. It's too big a group to have a main event talent attached to them, because there's no way on earth at least 3 of them won't get buried. Add to this the fact Triple H was taken out by a heel and the current champion, and it would become illogical for him to come back, ignore that it happened, and be a heel himself. Unless of course they go down the route of him returning, beating up Sheamus, and THEN going heel... but I genuinely don't think it'll be Triple H.
Chris Jericho is in with a shot as he's manipulative, power-hungry, and a firm ally of Wade Barrett and openly supported the attack on Cena. However if you believe rumors there's heat on him for hosting Downfall and daring to exist outside the WWE. Seems a crazy rumor because they are promoting it on their site, just as they promote almost all of his extensive media appearances, and if they felt like it, they could just tell him no. But even if we ignore that, I don't think they'll let him be the GM. Before it was implied that the never-mentioned-but-assumed secret leader of Nexus/NXT and the new GM were one and the same, I'd say he had a chance, but Jericho as GM doesn't seem likely, even if I'd like to see him in a suit cutting promos every Monday, it'd mean he surely couldn't wrestle as well, and it seems a little early for his retirement.
Stephanie McMahon is heavily pregnant and off the list.
Shane McMahon isn't even with the WWE anymore as an employee.
Paul Heyman is done with wrestling altogether in my opinion. Sure, he writes columns about it from time to time so evidently still watches enough to know what he's talking about, but I just think if he wanted to get back in he's had his chances, so think he's happy doing what he's doing and not interested in coming back. He also hasn't been mentioned in any way on air pretty much since he left the company.
Wade Barrett himself gets mentions but I don't think it'll be him as his wrestling career has just started. I don't think we can have an active wrestler be a GM because what stops him from making a 20 on 1 handicap match against the champion wherein the 20 can use weapons and the 1 can't, and the title can change hands via DQ or count-out? I could maybe see one of the older wrestlers like Triple H or Jericho stepping back, but Barret JUST got officially hired on-air, so I can't see it from him. I think he'll be the spokesman for the group and their wrestling leader, but he'll be taking advice from a higher power.
William Regal is another dark horse. He's been very quiet over the last year and his temporary stretch as GM and King of the Ring was pretty good in my opinion, although it contradicts my point about active wrestlers getting power. He and Barrett have the obvious Englishman connection, he was an NXT coach so knows all of them, and has been disrespected by all of the other pros. See his outburst in the finale for proof.
I still vote for Michael Cole, but Drew McIntyre and William Regal are my dark horses. I lean towards a non-wrestler for reasons of booking logic, but Drew would fit storyline purposes, and Regal has been in charge before.