Laser Beam, I'm not sure how you can say the BTTF 2015 was "dystopic" hell, if anything (technological advancements aside) it was damn near
realistic! Many popular movies made in the 80s and 90s that took place in the future were dystopic with society having collapsed, etc. But BTTF showed us what it'll really be. The same old bullshit.
No cities and towns won't be painted in garish colors like Dr. Seuss just threw up, there won't be flying cars or hoverboards and people won't be using phone booths anymore (they rarely do now) nor will we be using thumbprints to pay for things or open doors but, pretty much, Hill Valley 2015 was pretty darn close to the "real future" just the same nonsense, different decade.
Also, Laser Beam thanks for pointing out that hoverboards aren't real. Because, you know, I was still kinda wondering.
The movie also does some interesting things with the future, first it presents the idea that even flying cars won't solve all our problems with traffic, all it'd do is move it off the ground and put it in the air. If we had flying cars they're not just going to let you go where-ever you want in the sky much like how even aircraft are handled there's going to be lanes and controls on it. The movie presents this when Doc grumbles about a Skyway being jammed making it harder to get to Hilldale.
It also presented the idea that playing video games "with your hands" would be considered similar to children's toys. I think with systems like the Wii and the controler-les systems on the table by MS and Sony we're on our way there.
The movie, although there's no suggestion of an internet, suggests an "instant media" with the roving robot taking the picture of the courthouse disaster moments after it happens. When can presume that if an internet does exist the news item would soon be on the page. It also suggests large corporations taking over the media as Hill Valley's local paper is replaced with a local edition of USA Today suggesting that USA Today had bought up local papers to have more a control on the news itself.
Marty's kids in the house have personal videophones they wear all of the time. Although they seem connected to the house's line it does suggest the "constantly on the phone" mentality many kids these days have with cells.
I think the future stuff is fun an interesting and, honestly, really could've been something if The Bobs took it more seriouly, had something more to do with Marty's kids and, well, could find something to do with Jennifer.
But I do find it a bit of a dick move that Marty has to make his own decisions that'll throw his family lineage off course but his kids need help. His pause in the changed Part 2 opening after Marty asks if he and Jennifer turn out to be assholes even
suggests that
he knows Marty and Jennifer do not turn out okay! But, no, Marty cannot be saved from fucking up his life but
dammit his son is going to fuck up and must be stopped! (And while what Marty and Marline do certainly would mess up Marty's line in the family, one could presume that Dave's line would not have been messed up.)