Back to the Future director Robert Zemeckis has claimed on several occasions that there won't be a Back to the Future 4. However, the franchise recently topped a poll of films that fans want to see return. When asked if he was still against making a fourth film in light of that poll, Zemeckis said that his feelings on the subject haven't changed.
In an interview with Yahoo Movies UK, the director was asked if he was still against making a fourth film. "Oh god yes," Zemeckis responded. "But I think what the poll is saying… they asked a specific question, so I guess they felt it was important to spend money to poll the world, and ask this question, but don’t you think we could all have just given them the same answer? It confirms what we all know, but what I think the fans are really saying is that we really like this movie and if it were possible I’d like more of it. But they understand that it can’t be done."
Although actors such as Christopher Lloyd have expressed interest in reprising their roles, screenwriter Bob Gale seems to share Zemeckis’ sentiments. In a 2008 question and answer session, Gale compared making any Back to the Future sequels without actor Michael J. Fox -- who has retired from acting due to complications from Parkinson’s disease -- as impossible.
Although it doesn't sound like we'll be seeing them again on the big screen any time soon, the adventures of Doc Brown and Marty McFly have lived on in comics and other media. IDW Comics has explored the franchise with a recently concluded ongoing series, a mini-series examining the alternate Biff Tannen timeline created in Back to the Future II, another mini-series adapting Back to the Future: The Game and anpther ongoing series detailing the adventures of Doc Brown, Clara and their family on Doc’s Time Train, which appeared at the end of Back to the Future III.