io9 interviewed Steven Moffat and managed to get a few interesting bits and pieces from him.

Asked about the mention of the Valeyard in The Name of the Doctor and whether it was a hint of things to come: “Well, I couldn’t resist saying ‘The Valeyard,’ because we haven’t mentioned him in the new series. [Laughs] So I thought, ‘I’ll just put that one in.’

He added: “I never quite understood, in ‘Trial of a Time Lord,’ what he was meant to be. I never understood if he was a real Doctor, or [something else]. But in a story where we are hinting that the Doctor has a hidden chapter to his life, it was irresistible to mention the Valeyard. But you know, he’ll only ever get so dark, let’s be honest. He’s the Doctor. I think a man who worries about going bad is never really going to go bad. Maybe not…”

Moving on to River Song, Moffat says he’s “not quite sure” yet if she’ll be back: “I mean we can see her again because everything’s out of sequence and clearly the implication is that she’s met more than two Doctors. But the question is whether or not we should revisit her. It’ll now be story-driven. If we’ve got an idea that she fits into perfectly then there’s no reason why we can’t do it, but I quite liked where we got to at the end of ‘The Name of the Doctor,’ with him saying goodbye to her. So we’ll see.”

Moffat was also asked whether he thought he owed the fans some onscreen closure to some loose ends, such as the TARDIS explosion in Series 5 and the Silence: “Well, we are going to do it all. It’s going to end at Christmas. Yeah, [there will be closure]. But ‘owe them’? I don’t know about ‘owing.’ But yeah, there’s a plan, and we will end the Eleventh Doctor’s run with the answers to some of those questions.”