I've only seen the last trailer, and now the ad... but my predictions on the overall Rey/Luke/Kylo arc (from what I've seen and what I can guess by story tropes and the attempt to spin them) are as follows:
(I note here that these may have been discussed or theorized, but I haven't been following theories... so maybe I'm repeating them)
Rey - Is turned by Snoke
They don't want to repeat story beats again, so gotta flip em. Someone above said something about not holding Rey as so precious. I agree. No one wants to see their hero fail, but that's exactly what happened in ESB.. seeing a hero smacked down is good for the audience. You need your "all is lost" moment, and in a trilogy, that would be at the end of the second flick. So Rey will turn. People will be upset. But I was upset when Indy couldn't fight the Blood of Kali.... So suck it up.
Luke - Is brought in to bring back Rey after he turns her down and ends her training... leading her to Snoke.
This is a weird one, and the one I am fuzziest on... Luke will be a hero figure, but not til the end of this flick. We got introduced to old lost Luke in TFA, we can't jump right into him being a hero cuz it's not earned. For some people "The Last Jedi" will be their first movie... always have to look at it like that. If the person Rey is seeking just says "Hey you found me, great, lets go kick ass!", that won't work for viewers. You need a "Too old to begin the training!" type reluctance. So since they can't have it be the same as ESB or feel the nerd wrath, this time you'll have Luke train her, get scared, and cut her off. She will leave because of that... and now he's responsible for her being open to the dark side...
Kylo - The failed student battles with his guilt, and turns to help the resistance.
This is going to be a hard one to Swallow... but I think Kylos gonna be burned by Snoke's love of Rey. He killed his FATHER for Snoke. His feelings that Snoke has eyes for Rey will be what makes him question whether Snoke IS using him... and that will make him not kill Leia. And once he realizes he's been used, he will try and make things right... and that will start with him ending the movie holding his hand out to his ex teacher to say "let's doooo thiiiiiis" and go get Rey back.
Finn and Poe - I dunno... they're just gonna be blowing up whatever the bad guy army has planned.
I'm almost positive that's the way this is going... and at the same time, I'll probably end up wrong about everything because of one thing I can't wrap my head around...
I just can't see them letting Rey be saved by two dudes.
Every trick or treat group at my door this halloween had a Rey involved.... girls have a hero. Can they wait a movie to see her fall and come back from it?
But how if Rey doesn't fall, it would be completely uninteresting to follow her story further.
So would Rian be able to talk KK into letting him break Rey, so that she can come back even stronger in JJ's finale?
I hope so.