1. Jake and Sadie try to go to the future, but Sadie doesn't get there (gets killed indeed/ the nature of the rabbit hole doesn't let her into 2011/ they do get there but a cat goes downstears and Sadie disappears due to reset/ they do get there but Sadie gets depressed and leaves/ they do get there but the new present is terrible etc), then Jake goes back to 1958 to meet Sadie again, but she only treats him with a modest respect, as he is 40 and she is 24.
Obviously that was in S. K.'s mind originally; it was a relief to read an idea about this possibility in Jake's thoughts, since it became clear then that the ending is different. Which is great. This ending would be so sad, I literally wouldn't handle it.
2. Another option: they do get to 2011, but Jake finds himself married to Christy (either he didn't stay in the ofice for too long reading Harrie's essay and picked Christy up when she needed it so she wasn't pissed with him and didn't leave him, or the guy she left him for wasn't born since he was Sadie's grandson).
3. Whatever can go wrong does so and Jake goes back to the Land of Ahead and finishes grading the goddamn four essays.
4. Whatever can go wrong does so, and Jake goes back in time, meets Sadie and John, finds out that John is a nice man, helps him to overcome his OCD and leaves the couple happy.
5. Whatever can go wrong does so, and Jake goes back in time, meets Sadie and John, finds out that John Clayton is not a real name, the real one is also Jake Epping, who came from a paralel reality where the nuclear war happenned indeed, and he is trying to organize JFK assasination to prevent all the tragedies of his reality as he believes that JFK is guilty.
6. As a matter of fact, Jake may also go to Bloomington, find a small kid Al Templeton and talk him out of smoking. Then find out that:
A. He never smoked but still got a lung cancer
B. He never smoked and is alive
C. There is no rabbit hole.
7. Jake goes to 1958 and talks Mimi from smoking too. And gets on with her.
8. Jim LaDue does smth terrible which flips the furure completely. Or smth great instead.
9. Jake and Sadie live happily in the future or in the past despite everything! (An impossible happy end)
10. Also, Jake rescues M. L. King and John Lennon. And Buddy Holly in 1959 (then "the music doesn't die" and D. McLean is poor and unknown.) And then he stayes in the past for another 50 years and multiplies everyone's happiness by preventing Munich in 72, *G. B. Election, 9/11 etc etc etc
11. As a matter of fact, Jake and Sadie can go to the Beatles concert!!! Was silently begging for it throughout the book...
12. As a matter of fact, another sad ending would be if Sadie wouldn't know anything about Jake's real story, then he would disappear and she would kill herself in a few years after going to the Stones concert.
13. Another option is Jake disappearing and Sadie waiting for him to be born. She might then travel to Wisconsin in 13 years and become his baby-sitter.
14. Or maybe Jake could meet her in her 80s indeed (visit her in the hospital with a poundcake), but actually tell her the whole story, right before she would die.
15. Or maybe Jake would just sit there in 2011 all sad, but then thought that there exist a string, where he and Sadie are together and happy for their lifetime... And even though he isn't in that string, it makes him a little reliefed.