So to summarize... I'm not saying this cut would make TLJ a better movie, but this little piece of Skywalker's death being removed would make a heck of a lot more sense in serving as a pillar for how Episode 9 sets up. Even if Luke passed in the next film, fine... but it would probably in a blaze of glory instead of how it was done in Episode 8.
I think it would have been more obvious how the story would move forward, yeah. I'm not sure I agree that that's necessarily a good thing, though. Personally, I like the sense of having no idea where this goes next. They could end up completely botching it, of course, but I think there's a lot more potential to do some really interesting stuff with the series.
We're now all to assume Rey just magically becomes this amazingly skilled Jedi leader/master/something who will succeed Luke who barely begun to train her.
To be fair, that's basically where we left off with Luke at the end of ROTJ. Or for that matter, between ESB and ROTJ. At the end of ESB, Luke quit his training early, ran off and got his ass kicked and his hand cut off, and built a new lightsabre. He also now has funky new powers like being able to choke a pig guard, and he's a lot better at blocking blaster bolts and lightsabre fighting. It's never really explained how. The theory is "Oh, he trained on his own in between." (Kinda like his newfound ability to move stuff with his mind coming out of nowhere between ESB and ANH after a nanosecond's worth of training by Ben.) There's no reason we can't assume that Rey -- with the copies of the Jedi texts -- couldn't teach herself the same way Luke apparently did.
And that stacked on top of the Supreme Leader Snoke killed off before explaining his deal in all this are just 2 major blows that leave many of us really wondering what is left to tell that is going to wrap up a story that appears to be wrapped.
Perhaps they need to nix the tradition of trilogies and just keep these episodes coming as a continuing story so that it leaves more question as to who really would live or die and when. There'd be no knowing if say Kylo was going to die in Episode 9 or 11, or at all for example.
I think you've nailed it here. I actually think it's basically impossible to wrap the entirety of the story introduced in TFA in a single trilogy. TLJ left too much of a power shift to make up the difference from "We're down to everyone on this single ship plus a fledgling Jedi" to "We've defeated the First Order! Yay!!!" in a single movie, and I really, really,
really hope JJ doesn't try to do just that. Even with another massive time jump, it'd be too big a lift, too much of a "tell, don't show" and it would really hurt the story.
Here's my vision of the future.
Ep. IX essentially wraps up the Skywalker saga, in the sense of the Anakin-to-Luke/Leia saga. Leia will almost certainly die in this film, and Luke's spirit will likely only stick around long enough to either torture Kylo, provide some additional instruction to Rey, or a bit of both. Then he, too, will move on. The Resistance/Rebellion/New Rebellion (not sure what to call it?) will catch fire for real, while the galaxy falls more under the rule of the First Order (FO), although the seeds of the FO's eventual destruction will be sown. The Jedi will rise again, but in a new form, as taught by Rey (who may or may not actually lead them). The new Rebellion will score a major victory of some kind as well, albeit more one that signifies joining them is a viable choice, rather than one that destroys the FO outright. Much like Luke's last stand on Crait, the New Rebellion will inspire more people to join and fight back, and eventually retake the galaxy....which will be the plot of the next trilogy.
Personally, I'd like to see the FO start to splinter some from within. Perhaps a leadership struggle, involving the Knights of Ren, or at least one of them taking over and deposing Kylo Ren. I think Ben is
perfectly positioned to undergo a face-turn, if not to a true hero, then at least to an anti-hero, which would be really interesting to explore as part of a redemption arc in a subsequent trilogy. I think this could happen alongside Rey's growth in power, and perhaps they and other Jedi could work to take down the FO eventually in another series of films.
Or, as you say, simply abandon the notion of trilogies, given how restrictive they are and just...you know...tell stories. Each film fits into the overarching story, moves the ball a bit, and it keeps going and evolving over time.