Besides, it only makes sense. How else to resolve Ten's "Last of the Time Lords" issues without the return of the Time Lords? Hard to imagine ways to pull that off storytelling wise.

Well, RTD could always use the "it was all a dream" copout to remind the Doctor of just how goddamned much he used to hate them. (With the shot of android!Master in the trailer, though, I'm thinking some weirder, partial resurrection. Regrettably not featuring the Valeyard.)