No, Heller will not be overturned outright. The Second Amendment will continue to protect and individual right.
BUT, don't expect to get any more protection out of it than we already have. A Supreme Court with Clinton nominees will, best case, continue to deny cert to most petitions that implicate the Second Amendment. At worst, they'll start taking 2A cases with the intent of limiting the right by ruling against on on things like carrying in public, sensitive places, prohibited persons, and arms in common use.
The core holding of Heller will remain. The court simply does not 180 degree turns on major issues very often and when they do they let generation pass between conflicting decisions.