Back to the Future: Great Scott, WHAT IF?

Okay, so I rewatched Back to the Future last night (again...don't judge!). Still holds up, no doubt. But it got me thinking about Doc Brown's whole 'roads? Where we're going we don't NEED roads' spiel at the end. I mean, clearly he was just stoked about flying, but did he ever actually use that function again? We only see him flying in the animated series which, let's be honest, isn't exactly canon. I'm imagining Doc accidentally landing the DeLorean right in the middle of a rodeo or somethin'. And speaking of Doc, what's everyone's favorite Doc Brown moment? Mine's probably his reaction to Marty playing 'Johnny B. Goode'. "This is new! This is… heavy." The man's mind was BLOWN. But then you gotta wonder, did he ever try to 'invent' rock and roll when he got back to the future...future? That concept kinda messes with my brain. Also, that entire Enchantment Under the Sea dance sequence is iconic, right? Lorraine falling for Marty instead of George is hilarious, but also kinda creepy given it's his Mom. "Is my fly open?" Always cracks me up. Anyway, what if, hypothetically, Marty hadn't gotten them to kiss? Would he just...fade out of existance? Or would something even weirder happen? So basically, what's one BTTF "what if" scenario that keeps you up at night? Let's hear 'em! (And nobody say director is unknown...it's Robert Zemeckis, lol)