From doctorwhotv: Many fans have speculated on a multi-Doctor story since the show came back and with the 50th anniversary in 2013, it would seem like the ideal time to do one.In an interview with Digital Spy, Steven Moffat has said he wouldn’t rule one out provided he had a good story.
“It’s slightly difficult to do them all now. I’m not against it but I think as a gimmick it outlives its usefulness quite fast.” He said.
Moffat continued, “Doing Time Crash with 8 minutes of Peter [Davidson] and David [Tennant] was about right. If you have a really good story that motors on the fact that this is one man experiencing the same adventure at several different points of his life, that would be worth doing. But you can’t do a special or an episode as a reunion party. That’s not a story, that’s a party. Nothing wrong with parties but they’re not great fun to watch. But with a really good story, then yes.”