Regardless of what's being brought back, I'll be glad if it's almost literally ANYTHING other than the rainbow corps. It was a good idea that's been used to death. Hopefully after the first arc of both books we'll be seeing less of the other lantern corps.
One thing that sadly won't be coming back since Hal will be in space is his identity at Ferris flying planes. There's nothing more classic than that.
Personally, I'm hoping for Evil Star, the Controllers, a visit to Thanagar, Pol Manning, the Spider Guild, a sun-eater, the Space Ranger ... all sorts of outer space goodies that have been on the shelf since Geoff introduced the Rainbow Brigade.