The trilogy is a mess precisely cause nothing was planned out ahead. If this time travel nonsense was something they wanted to go for at the beginning, they sure fucked up by a) choosing the most asinine bullshit plot element of all times and b) fucking up every step of the way to that plot element.
I think if time travel pops up, it's just the most massive way of retconning their entire fucking trilogy out of existence that they could find since they are aware that their trilogy killed Star Wars and they need to undo it.
Such time-travel-shenanigans are frowned upon for a reason, it means nothing that happened really mattered.
That being said, I really hope they'll make Rey go back in time to become Shmi. I really hope they do the most idiotic things with Palpatine.
This movie has to alienate everyone as much as possible, so even the shining lights and bright explosions and massive lensflares will not manage to distract the audience enough for them not to realize just how fucking dumb the movie is that they are watching.