My take on predicting Doctor Who
There is a lot to say about what happens after the cliffhanger at the end of Series 7 of Doctor Who, and there's already many speculations on the Internet about it. I'm going to give my own version here. Careful tho: spoilers ahead. If you haven't seen Series 7 yet, please stop reading now.
At the end of The Name of the Doctor, we're faced with this obnoxious reveal: http://www.youtube.com/watch?v=Oki58yhj1b0#t=30s and everybody started racing to explain what it means exactly, and what we might expect in the 50th anniversary episode. Now as I said, there's already many speculations, and the most popular one is that John Hurt is in fact the incarnation of the Doctor who ended the Time War by killing all the Daleks and Time Lords by probably some sort of doomsday device. But it doesn't exactly matter about what he did truly is. The "Time War" thing at that point is merely a plot device that says "he did something very bad, and that wasn't in the name of the Doctor." So even if that isn't Moffat's idea, I'm going to stick with it, as it is of no importance.
The same speculations are also saying that since Christopher Eccleston started talking about the Time War, and that we never heard of it before, it must have happened between him and Paul McGann. And since we never saw the 8th Doctor regenerating into the 9th, (but we know that Christopher played at the beginning of his regeneration), there's an easy deduction that is that John Hurt is in fact the 9th Doctor, that Christopher is the 10th, David the 11th, and Matt the 12th. But quite frankly, I find this too easy from Moffat. That, and it would trigger a schism in the Whovians fandom between those who want to renumber the Doctors accordingly ("because, well, John Hurt WAS introduced as "The Doctor", right ?"), and those who want to keep the current numbering ("but he said he did things not in the name of "The Doctor", so he doesn't count!").
Now what do we know... well, Moffat loves time loops, that's a given. He also loves having several doctors together (even though this makes a pair-o-Docs, ha, ha, ha). And his typical plot scheme is that the future version tells the previous version how to solve the problem at hand, and everything's fine because then the previous version will later be able to become the future version and tell the previous version what to do, because he "remembers" what to say... Wibbly... Wobbly... Timey... Wimey... Anyway. We also know that the 50th anniversary will feature a ton of Doctors altogether. If he could, he would've gotten his hands on Eccleston as well. So I wouldn't be surprised if that episodes somehow features all the Doctors together one way or another. Or a good portion of them.
I've also always considered very odd that he actually survived his doomsday device, killing all Daleks and Time Lords, and somehow survived. My take is that he didn't. My current theory is that John Hurt isn't the next, nor the 8.5 Doctor, but he's the last one. He basically goes and sacrifices himself and all of the Time Lords in order to wipe the Daleks and end the Time War.
Which means that the "Doctor Who" story (probably even from the very beginning) isn't about the Doctor fleeing his past and trying to repent from what he's done, but rather about him repenting from what he WILL do. And it doesn't matter if it's in his future in his timeline. What matters is that it happened, in a fashion that he knows exactly what will happen in the future, and this will be a fixed point in time that he will never be able to change.
I realize that this is a rather tragic story for him, since it doesn't matter how much good he will do during his long life, he knows that he'll kill everyone in the end. But all in all, that kind of time-loop is very Moffat-y, and I'd like to think of it this way.
Anyway, my two cents