It's been announced that Christopher Eccleston will not be returning for the 50th Anniversary special. Now, this could be just another one of those little lies that makes up what I've been calling Operation Blue Harvest, but this one is probably true. Eccleston has been very adamant about not wanting to come back since the beginning.
Let's be honest, Eccleston was never really that interested in Doctor Who. Tennant was a hard core Doctor Who fan from childhood. Matt Smith had never seen the show when he started, but he watched a lot of past episodes as research for the role. Eccleston not only had never watched an episode, but refused to ever watch any past episodes to make sure that he wasn't influenced by other people's performance, which is the worst possible way to play the role. When asked why he wasn't going to put on a more elaborate outfit, like past Doctors, he said it was because his Doctor wasn't going to be a "tosser."
There are some Doctors who, when put up next to each other, are hard to believe that they're the same person. 11 and 1. 6 and 4. 8 and 2. But when you watch them all in order, there's a kind of natural progression of his personality that makes sense, so you can kind of understand how these different incarnations are actually the same person. But if you put 9 up against any Doctor, even the ones immediately before and after him, it's almost impossible to believe that he's supposed to be the same person. Even 10 and 9 don't seem like the same person, nor do they seem like they would like each other. 9 would find 11 insufferable.
Eccleston didn't take the role out of any interest in sci-fi or Doctor Who. He actually took the role because he wanted to work with Russel T. Davies. I don't think he knew what he was getting in to. I don't think he understood that Doctor Who is a huge franchise with fervent fans who devour the expanded universe media and who want to see the past characters and actors come back. I don't think he realized that anyone would want him to return after he was done. He also had some difficulties with Davies behind the scenes, which have only been referred to very vaguely. Hence his early departure. No matter how much the fans want him back, I doubt he'll ever make another appearance on the show at any point. There aren't going to be audio stories about the 9th Doctor. Eccleston isn't interested in being a Doctor for the rest of his life.
However, the fact that Moffat met with him tells us that they're trying to do a big Doctor special. Especially if Eccleston and the show parted on bad terms, the fact that anyone would consider calling him means that they were very interested in doing the special with multiple Doctors. I'm frankly shocked that Eccleston even took the meeting.
If it's true that they intend to use footage of past Doctors, its possible that they're shooting to have an Eleven Doctors special after all. As "The Five Doctors" proved (and, to a lesser extent, the super non-cannon "Dimensions in Time"), you don't need all the actual actors around to make it a multi-Doctor special. I know there are those who really love Eccleston and want to see him back, but I think fans of the modern Who will be fine with just the Matt and Dave show. And the classic fans will be happy with anyone from the classic series they can get (well, almost anyone).
And if Tom Baker comes back, then all will be forgiven.