I actually think that's a cracking idea. Maybe going a bit into Valeyard territory, but I think I'd prefer it if it was just a regular, well-meaning future-Doctor who is forced into it somehow. It could be even more dramatic for the current Doctor to be haunted by the past events because he knows that he's actually going to have to go and do it at some point in his own personal future.
Yeah that was more my thinking as well.
I can see the scale could be an issue but not mentioning his future self was there isn't really. That's what he does all the time, hand out those vague snippets of what went on in the past, which is why I thought McGann could fit even though at face value you'd say it was Ecclestone's Doctor that was there.
That's fair enough. Though my impression always was that it was in fact McGann, not Ecclestone, who was there. In the first episode of the new series it's pretty clear that he's only just regenerated. There's the scene where he looks in the mirror and checks out his new features.