Robert Zemeckis has stated that Back to the Future 4 will never happen, and while this is probably good news, there are some things which a sequel could have delivered. The Back to the Future trilogy came out between 1985 and 1990, and although there have been some calls for a sequel, many fans are content to leave it as it is. This makes Back to the Future a rare example of a franchise quitting while it was ahead, ensuring that it's legacy remains intact.