I've been thinking of writing my own story for Back To The Future Part IV.
I would have to keep it true to the franchise.
I've had ideas such as a new protagonist, I'm thinking maybe a younger sister of Jennifer Parker/McFly called Daisy Parker who is 24 in 2015. But the future isn't how it should be. There are no flying cars, in this world, flying has become a real ordeal due to terrorism, there are no actual hoverboards, there is something which has two wheels which is called a hoverboard but it just like a Segway without the tower. No home fusion reactors, self-lacing sneakers, dust-repellent paper, and in general things haven't pretty much changed in three decades. I saw a video on YouTube by CollegeHumor which addresses these issues, indicating how little we have actually progressed as a society.
Anyway, Daisy is like Rey in The Force Awakens (the name is even a homage), she is a techy, and is searching a junkyard for scrap she can sell or repair. She happens upon an old DMC-12 model DeLorean, which has numerous modifications for an unknown purpose. She finds the car has advanced technology, and labels from companies which she has never even heard of like Fusion Industries. She perhaps also finds the real pink hoverboard, and realizes this technology came from a different time. (These are all just ideas, don't take this too seriously yet). She manages to awaken the car's power and it illuminates from within, including the flux capacitor and the time circuits.
Now I'm wondering if she is chased from the yard by the police or something and escapes by hitting 88mph and goes back (or forward) to an unknown time. The story could revolve around finding Doc Brown who is maybe lost in time. It could feature Marty as a father, who knows things are not as they should be, but has no way of doing anything about it. Perhaps Marty joins her in the search for Doc Brown. Also, the DeLorean being in that Hill Valley junkyard is mystery in itself, another question for another time.
The plot will have to feature the Tannen family, maybe even Edna Strickland who appeared in the game could be a villain. Ideas for what became of Doc, his family and the time train include it being stolen, malfunctioning, or irreparably damaged. If the technology was stolen, maybe Tannen Industries/Tannen-Tech are trying to unlock the secrets of time travel and also seek the Doc, which could maybe tie in to him hiding the second DeLorean inside a junkyard under piles of scrap?
Also had ideas of a futuristic DeLorean, one which is sleeker and more advanced than the original which is retro but classic. The futuristic model would have to have advantages but one large failing...Doc Brown didn't make it. Based on his technology but not 100% safe. In order to save the past, present and future, our protagonists must come together to stop not just Hill Valley, but perhaps even the world being reshaped in Biff Tannen's image.
All ideas, all disjointed, but maybe it is possible. What do you guys think, worth giving it a go?