I think that somehow the original Doc returns to the game. Later Edna is almost arrested by Officer Parker for the speakeasy arsonist. However she jumps into some vehicle ( possibly the flying car or DeLoreon) and drives off. But the vehicle malfunctions and crashes into the Doc's wife Clara's Ravine and gets trapped or becomes dead (shown off camera though). FC Brown later reappears somehow and tries to stop himself from doing anything and causes all innovation to stop in Hill Valley. He is later destroyed but Doc and Marty have to worry with a busted Flux Capacitor, which was made faulty to begin with. They see the future based on what happens in modern day time. And finally makes it into the correct time. Doc stops the estate sale and moves his family into the house ( with expansions to it). Marty and Jennifer see them in their house and everything returns to normal. Until something else gos wrong that is!
Comments
http://www.youtube.com/watch?v=1qP-NglUeZU - Yeah, I couldn't help myself.
If you called Sylvia being Trixie under a "stage name", pat yourself on the back
If you ascertained there'd be a BTTF Animated Series reference in the game, give yourself a round of applause/standing ovation.
If you called there'd be a hoverboard involved... well seeing it was it's own reward :P