Yeah... I get the impression that all of Moffat's dangling plot threads (what made the TARDIS explode, who the fuck are trying to build their own TARDIS and why and how, wtf Silence, the Fields of Trenzalore) are one big long game leading up to the 50th. I also kinda think he's trying to clean house after RTD broke the Doctor and didn't put him back together again, and giving the Lonely God/Woobie Destroyer of Worlds stuff a good sendoff before he kills it dead. And... I honestly don't know what he'll do with himself afterwards. Presumably he's trying to leave the house in good shape for his successor, but no idea whether he'll stick around to enjoy it himself.

I do hope Matt Smith stays on after Moffat leaves though. He at least seems to be showing no signs of burning out, and I'd love to see what a different showrunner would do with Eleven.