Let's say Matt Smith leaves after the current series or is still undecided, if he returns...
What do you think of McGann returning in a special prequel year similar to the Tennant specials after series 4?
They could end with his regeneration into 8 or leave his fate open for later appearances, but give him a few key stories, foreshadow events we know are coming for later doctors or set up stories for 11 and 12 to give them bigger scope and meaning.
Yes, yes, a million times yes!
I'd give it to RTD to do though. He seems to have a style more like the 96 film that Moffatt, I think he'd pull it off better, or maybe a combination of the two. Or why no just give it to the original crew to do???
Either way if it means getting Paul as the doctor again, YES!!!!!!