Steven Moffat on Sherlock S4

What he said at the Emmys:

“We have a plan to top [the season 3 finale] — and actually I do think our plan is devastating,” he said in comments shared by the Hollywood Reporter. “We practically reduced our cast to tears by telling them the plan. Honestly, Mark [Gatiss] and myself are so excited with what we’ve got coming up, probably more excited than we’ve ever been about Sherlock."

Source

I bet they plan to kill off Mary. And possibly their child, too? Or maybe John will leave his daughter with the Holmeses? I mean, that's the only way how they will ever get a grandchild, after all. But I do think Mary is goner. I don't want to lose her, I fell in love with her so hard - on the other hand, I bet it'll be AMAZING! \o/