Series ending theory
Now mind you this is just a theory and it's too bad that after the show ends, we won't be able to talk about it but....
I think that Bonnie is going to get her Magic back and turn all her vampire friends back to human and they all live happily ever after and all die old together. Since Elena and Stephan are no long living forever, the other should do the same.
I don't know, that is my own cheesy theory. But no matter what, I'm so gonna miss this show. Ithe Vampires Diaries have been my life for over 10 yrs. I read the books before the show started. Thank god for Netflix and Blu-Ray