So in the instagram pic that was from filming the premiere, you can see that Elena has the red stripe in her hair which Katherine, of course, got rid of. So, I'm thinking that, yeah, we're gonna get flashbacks of Elena and Damon's summer of love! Woohoo! Which would make sense that Elena is thinking back on that time. Or at least that we'll be definitely getting flashbacks of when Damon and Elena were together and that's how we'll get Damon/Elena scenes even when they are separated. So, WOOHOO!
Secondly, the episode title is apparently "I'll Remember." Now that fits the Elena flashback theme, but I was also wondering if maybe florencia7 is right and Damon and Bonnie are going to have amnesia. Maybe, just maybe what Grams did is send Bonnie back to Earth, but with no memories and that will be the case with Damon and Bonnie both--since he was with her, duh (much like in florencia7's story--which you should check out, it's pretty good!). Hmmm...........
I didn't think they'd go there, but with that title, I'm wondering now. Just wondering.
ETA: I forgot to put this in here (which I meant to, but sicko1012's post reminded me. They briefly touched upon this with Stefan's memory loss arc in season 05, but the show tends to do that. Briefly do an arc and then do a longer take with another character in another season. For example, they did it with the possession of Matt/Gregor briefly, then much longer with Elena/Katherine. Did the sire bond with Tyler/Klaus and then did a much fuller exploration with Damon/Elena. I don't think it would be redundant, if it's explored much more richly and thoroughly.
Also, PLEASE don't further spoiler me on anything else in the season. This is all I know and I don't want to know anything else.