This is actually an interesting question, as the Krynn have barely shown up in the campaigns. They were mentioned in the DA campaign's epilogue, and they showed up in three missions in TOA as a neutral faction that helped fight the Dread Lords... other then that, nothing. I think they weren't in Brad's original stories either.
From their tech tree, their backstory seems tied into the underlying mythology of the game (their creation myth is similiar to the Precursor one), more so then the Korx, who also had little to do in the campaigns. So this might mean the Krynn have some sort of role to play, or it might be just that they were supposed to have a more interesting backstory.
It's not likely they'll be joining up with the Drengin, though. In the long run the Drengin intend to conquer everyone, and I'm pretty sure in GalCiv 3 either they'll back-stab the Yor, or more likely the Yor will back-stab them. I doubt they'll be making any new allies.
Edit: Also, you seem to have posted this twice.
