I would guess that ROH felt it would be bad for the company to lose them in the same year as Nigel and Dragon, because that's 3 of the companies most over, most historic acts all abandoning ship at once. So they said "Can you please stay, if only just for one last title run?" and the Briscoes thought why not. We waited for the best part of a year for Mark to be healed up enough for them to return and if they'd just signed with WWE or TNA a few weeks later it would have been a bit of a slap in the face to the fans.
I have no doubt they could do well for themselves in either company, probably TNA more-so as they are more adult orientated and have better teams to work with there, but I'd rather see them stay. There are so few ROH originals left and they're going through a difficult re-building stage, so it would be good for the company if they stayed with them through it, at least until a new act can step up to replace them. Dark City Fight Club probably just aren't going to cut it, and the Wolves and Kings of Wrestling are phenomenal... but they're heels.
People say they couldn't work in the WWE because they swear, but there's a simple response: don't put them on Raw. Tape their promos so you can re-set if they drop an F-Bomb. They've cut promos on HDNet in front of a live crowd and managed to control themselves, plus, they are grown men, I'm sure they could handle not cursing if they were paid not to.
Also, with Mark's (hopefully last) injury he has been forced to ground himself and stop doing the shooting stars to the outside and other crazy dives. They've become a more traditional tag team because of it and would fit in with the WWE a lot better now than they might have at the peak of their popularity and quality. ROH fans seem almost annoyed at the Briscoes at times for not having Mark kill himself in the ring, but those are not good fans.
I'm really not sure where they'll end up, but I'm pretty sure that they won't be in ROH this time next year. They've done absolutely everything they could possibly do here and faced every team that's been assembled while they're active. Neither is ever going to conjure up enough solo support to make a legit run at a title (if the TV title had come along during Mark's injury Jay would make a good champion) so their days have been numbered for quite some time. They'd tear the house down getting to face the likes of Beer Money, MCMG, Team 3D, British Invasion, Lethal Consequences and ummm that other team (I hate the Young Bucks a lot) and they'd fit into TNA really well, but I think they could get over in the WWE too given the chance, I was just surprised Vince was interested, maybe he doesn't hate tag team wrestling after all eh?
