The fact that Moffat can't keep dead characters dead cheapens Doctor Who a lot more.It cheapens Doctor Who with another virtually immortal person
The Time Lords have secluded themselves at the very edge of time and space to avoid everyone who wants them dead, and the Doctor is presumably doing his damnedest to avoid Gallifrey after Hell Bent. So there aren't very much possibilities anyway. Besides, Moffat has admitted it was a mistake restoring Gallifrey in Day of the Doctor, I don't think he wants to write about the Time Lords. The only reason he revisited them in Hell Bent was to resolve the story he set up in Day of the Doctor before he stepped down as showrunner, which he was planning on doing after writing The Husbands of River Song, the very next episode.I'm glad they've brought Gallifrey back completely, thus abandoning the "Last of the Time Lords" story which was beginning to get stale, and opening up future possibilities.