Board Thread:General Discussion/@comment-28824622-20161003050849/@comment-29926185-20161018212746

Rigby and Eileen getting married doesn't seem too far-fetched, although... Actually seeing the wedding kinda does. You know what the show's like with Eileen - Rigby and Eileen might get engaged (or maybe they already did and we don't know?) and if they do I doubt the show will make a big deal out of that.

That said, I think as far as my prediction goes, I'm gonna go with something kinda crazy:

Mordecai is killed during the battle with Anti-Pops, causing Rigby to go back in time (he can do this with his spaceship, as we saw in the movie) and erase the timeline of the entire show by preventing them from getting the job in the park in the first place, to prevent the series of events that led up to Mordecai's death from ever happening. Rigby realises that this might change a lot of the good things that happened to him too, such as meeting Eileen, graduating from high school, etc.. but doesn't care about that, as long as it means he doesn't have to lose Mordecai.

Then, as 'end of season 8' Rigby fades from existence, 'pre-season 1' Mordecai and Rigby, who were about to go to the park to ask for a job turn around and walk away... and Mordecai gets run over by a bus and dies (call the episode "Blue Jaywalking"), and 'fading from existence end of season 8 Rigby' sees it and is like "noooooo!" and then disappears... The end.

Ok, Ignore that last paragraph, I got a little bit carried away :P