OKC seems to be the general rumor. Does Edmonton still own the franchise, then the local guys listed as "owners" on the website own the management company? That seems to make the most "sense", but that doesn't mean much in the AHL. Drawback would be the distance from Edmonton to GF, but that has been worked through in the past.
Portland has been rumored as well, but I would guess that their ownership would want everyone to know where they were to use it as leverage with the officials in Maine..... Similar to how they visited Albany in 2010, no secret.
The ongoing rumor will always be Rangers, if MSG can buy/gain operating control of the arena. Moving the team out of Hartford would most likely help Springfield actual attendance/sponsorship wise also.
I wouldn't be shocked to see the Devils move to GFCC either. The TU Center has made several improvement to keep the Devils happy, and if those had been in place 10 years ago it's possible that the Rats would never have left. (Way better ice, less aggressive security, better food, cleaner building etc.) I've also heard from former Devils employees that the arena may poach advertisers from the team and offer them a different deal in the arena. There is an airport a few minutes away from the GFCC that is big enough for Lou L's plane, so don't worry about that. Devils do have an arena management company, so if they can manage the arena overall I wouldn't be surprised to see them move 51 miles up the road.
Robert Esche was quoted as saying he'd talked to seven teams about moving to Utica. The situations are very close, except if the owners can run the GFCC they might be able to make some more money on concerts, etc. Plus it's not shared with a college team. So it's possible there are six teams that could be interested in discussions at least.
Never minding the "announced" attendance, there are as many or more people in the seats in GF than in at least the bottom third of the league (maybe even half). The employees like security, concession, cleaning, etc. are paid close to half of what they get in Albany (union vs. non-union shop). Most of them do a better job in GF also, which is interesting. The crowd, overall, is quite thirsty- there are a lot of concession sold compared with other arenas. And the fans buy merchandise- they go through about eight sets of game worn jerseys a year and make some good money off them. It's the only show in town also, which is a plus. And keep in mind the team has stunk all five seasons they've been here, and the last time the Red Wings put a team that really threatened anything was 1993-94.