okay but if Ford lives long enough to see the niblings grown up then what if he’s the ‘travelling grandpa’?? like the same way that Stan stays in Gravity Falls Ford travels around the world investigating how the Transcendence affected the once magic-free lands, probably getting in touch with various magical cultures and even (?) rising as a world-renowned preter scientist (who apparently’s been studying the supernatural long before the Transcendence happened). From time to time he goes back to Gravity Falls to visit his family, and this doubles also as a means of protecting them from too-prying eyes who’d notice if he lived there permanently. Of course, despite it all, it’s still Gravity Falls that feels like home. He probably has his own hand in the Pines becoming a semi-mythological name, with all his heroically-ridding-a-town-from-an-eldritch-monster-with-a-mixer-and-grinning-maniacally-at-the-result and other stunts around the world.
(Bonus points if Stan DID go with him monster-hunting for the first two years, but then decided to go back to Gravity Falls permanently for some reason or the other.)
(Further hc that he always leaves Gravity Falls with new sweaters, some bedazzled clothes and various drawings and presents the niblings made for him. Also up to date to the lattest gossip on Dumb Shit Dipper Has Done, some corrections on rumors he heard while traveling and new fascinating tidbits of information Dipper shared with him for a Snickers and a game of DD&MD like the nerds they are.)
(and further further hc that it doesn’t really sink in how bad Ford is at precaution and safety measures until he’s appointed as babysitter one time and the niblings almost get eaten by a mutated sandwich. Dipper becomes co-babysitter from then on, because apparently a literal demon is safer than an enthusiastic but forgetful scientist. It doubles as a bonding thing for the both of them.)
Also, please visualize Grunkle Ford talking about his adventures, both in Earth and in various other dimensions, to three starry-eyed redheads and one very amused (and sometimes downright sentimental) demon. (Dipper probably makes a deal at some point for visuals to go along with his grunkle’s retellings because danggg.)