I'm starting to fear my fellow Whovians are getting their hopes up WAY too high, and whatever Moffat and the BBC come up with this fall isn't gonna clear the bar. Ironic as this may sound, throwing everything AND the kitchen sink at the screen was a lot easier in 1983 than it is now.
That's possible, but they really need to do something like this or it's just going to seem like a lack of effort to many of us. It's a Who tradition to bring back as many older Doctor's as possible for these anniversaries.
Personally, I'd be totally fine if not all Classic Doctors returned, but the they do need to be represented.