Well, so much for the notion that she’s permanently dead and gone. Kingston’s River will meet Peter Capaldi’s Doctor for Christmas. How? Quoth the Moffat, in the press release: “Another Christmas, another special for Doctor Who – and what could be more special than the return of Alex Kingston as Professor River Song. The last time the Doctor saw her she was a ghost. The first time he met her, she died. So how can he be seeing her again? As ever, with the most complicated relationship in the universe, it’s a matter of time …”
Obvious fan theory: she regenerates into Maisie Williams somehow.
Even more obvious fan theory: Moffat is making this shit up as he goes along, with absolutely no plan beyond recycling things that worked before.
That said, Kingston is always fun, so she’ll elevate the material nonetheless.