A lot of people are speculating about who's gonna end up taking Norman out of power. Some think it'll be old rival Spidey, others think it'll be Iron Man getting revenge or Captain America coming to the rescue again. His "partners" seem like likely candidates too, since they all seem to hate him, judging by his portrayl in Thunderbolts and Dark Avengers. Or he might just end up screwing himself over- it wouldn't be the first time he ruined his career and his reputation just to get his kicks for a few hours flying around on a Goblin glider and blowing people up.
Quite frankly, though, I think the best way for Dark Reign to end would be for Norman to get his comeuppance from his oldest victim: The "Robot Master," Mendel Wardell Stromm. I recently heard that they brought Stromm back in the Penance one-shot, and I wouldn't expect them to bring up such an obscure and forgotten character unless they were planning to use him more in the future. And it would be the one ending practically no one would see coming.
Stromm was brought back during the Second Clone Saga in the late 1990s as Gaunt. Obscure, yes, but it has been done before and Stromm had been brought back as Osborn's lackey when he returned from the dead and was the leader of the Cabal of Scriers.