The IMDB stories are usually D.O.A., but this has comments from Fox himself, so I'm guessing this is closer to a reality than it has been...though there's no mention of "negotiation" in his comments proper.

Maybe Universal needs it after KONG, too


Fox Heading 'Back to the Future'?
Michael J. Fox is heading Back To The Future for a fourth time-traveling movie. The actor, who suffers from Parkinson's disease, admits he's in negotiations for a final film in the series - but only if they make his character as old as he is in real life. The former Spin City star wants to take over Christopher Lloyd's eccentric scientist character, Doc, in the sequel. He tells movie website Moviehole.net, "The only way it would work would be if I played Doc. I'm 44-years-old now and I'm not interested in running around on skateboards! I think after 1, 2 and 3 we all kind of felt we had done it. And I think if they did it again now they would do it with a younger cast and just do a different realisation of it, which would be fun."

Every bit as bad an idea as Indy 4. It'd just be too sad to see an aging, tic-ridden Fox trying to recapture that youthful magic again.

Then again, it'd give Elisabeth Shue some work...

I'd just as soon they not bother, at this rate.