Well, considering they've done a few "secret identity" type pieces, I wouldn't be surprised to see an extra head piece for Martian Manhunter if they do him. Of course, they may just go with his new look, which would be awesome.
Also, I like the Flash/Captain Cold idea. Heck, they could probably do a couple rogues only sets with the Flash and Batman villains. I won't be holding my breath for those but it would make me insanely happy.