So this idea could be called an alternate universe, but I don't think it technically is, since it would take place entirely after the show, with no changes to canon material.

I got this idea after I finished reading the Journal, so spoilers for that.

Fast forward four decades or so after the events of Gravity Falls. The grandchild of Soos and Melody comes to Gravity Falls to visit with their grandparents (whether or not they have siblings or people that come up with them is undetermined). Let's make them a girl, just because. This girl, the MC, is having a great time with her grandparents and "Graunty Mabel," a single woman not quite old enough to be a grandmother who isn't actually related to MC, but insists on the title regardless. Then one day, when searching the Mystery Shack, MC finds a curious book with a pine tree on the front, and four stars down the center of the tree. The author of the Journal refers to himself only as "Dipper."

As MC discovers some of the supernatural happenings around Gravity Falls, she meets Wendy Pines, Mabel's sister-in-law, and learns about Wendy's late husband, Mason Pines, who was lost in a tragic supernatural accident. Add in more characters, sprinkle in that classic Gravity Falls charm and mystery plot, and eventually MC discovers that Mason Pines and Author Dipper are actually the same person, and possibly finds Dipper too, who wasn't actually dead, just missing.

Anyway that's basically it but I wanted to share this idea for two reasons:

1) I like the idea of Dipper going by his real name as he gets older but using Dipper as a pseudonym/adventurer name (plus have you seen the Relativity Falls Journal design? so cool)

2) Regardless of my shipping Dipcifica I have a strong sense that theirs would be a teen romance, maybe a summer love. It would be great while it lasts, but when it comes to marriage and lifelong commitment, I actually think Wendy and Dipper are more likely to marry. Plus their kids would be the best little adventurers.

This idea will probably never come to fruition but I wanted to share it regardless! What do you think? (mostly about the two points at the end)