Maybe Chelsea?
I too wonder if Chelsea will pick up the gauntlet. She's never shown much interest in elected public office but maybe mom and dad will motivate her. I'd say we'll have a pretty good idea of her intentions in the next year or so as she'd most probably go for a House, or less likely a Senate, seat in the November 2018. With her parents getting a little long in the tooth and maybe not of the greatest of health she'd have to commit sooner than later if she was looking for their support.
Sanders would have been immolated by the GOP. Trump would have come off looking like General MacArthur standing up to the Communist Threat to take over the White House and the country.