That’s interesting you mention that, because I think that was a fundamental issue with early drafts of TFA. As soon as Luke is back in the story, the new characters suddenly felt like supporting characters. Michael Ardnt really struggled with that, and I think it was Kiri Hart who came up with the idea to make finding Luke the main goal of the first movie.

And while I personally think having Luke become one with the Force at the end of TLJ was not only thematically appropriate, but it also might’ve been sort of necessary to give the new heroes the spotlight for the last act of the trilogy. Yeah, I’m sure Luke will have a presence as a Force ghost to guide Rey, but Rey, Finn, Poe, Rose, they will be driving the story, along with Kylo Ren as the main antagonist for them to face, now that Snoke is gone.

And of course, it is heartbreaking that Carrie couldn’t film her last performance as Leia, but it is likely that Leia still would’ve been behind the scenes mostly, and I feel they will be able to fulfill whatever necessary role she was meant to fill with the extra footage they have. They seemed pretty confident that they have enough material (and aren’t they lucky they decided to cut a lot of her TFA scenes?). As long as they have enough for a few moments with the Resistance, and maybe one moment related to Ben/Kylo Ren, I think that will be enough. And by her playing a supporting role, it gives us more time for the young heroes to drive the story and be on screen together for the final film.

EDIT: Yeah, I’m definitely interested to see what happens with Hux. Either Hux tries to betray Kylo (which could be used to instigate Kylo’s turn), or Hux gets disposed of by Kylo, other First Order officers (or Stormtroopers turning against him), or just something totally random. I’d be surprised if he was just simply killed by the Resistance. I guess we’ll see though!