Three? Depending on who you ask, they’ve done it in two movies.
And playing aside, it’s hard for me to see where Ep IX can go and not only pay off its own story well, but fit in with the other two trilogies. Logically? If they really followed through on it - Kylo has a confrontation with his Mum and kills Leia, he kills Rey, or Rey kills him by going super dark side. Or full Spinal Tap: Aw, Kylo, you go up to 10? I go up to 11. But will that work when she’s already decked him twice? Vader, he is not.
(Insane stuff that probably won’t happen but who knows? They somehow kill Lando because… POkemon rules - Gotta got 'em all, right? That leaves Poe the last one standing, unless they blow up the Falcon with him and the droids in it.)
Because Jedi did it with Vader, I’m expecting Ep IX to do a redemption for Kylo. Like his grandfather’s it’ll be unearned and massively problematic for the overall story, but George did this first, OK? Oh and not to forget, the First Order will magically collapse completely by the end credits - again, see Jedi SE.
And that’s yer final destination for all 9 movies, a feel-bad finale because … expectations.
A damn waste. No one would have objected to a new enemy, that’s the foundation of any story and it has to come from somewhere. The kicker in all of this, which has been brushed over because the PT convinced LFL that SW fans don’t like politics - yeah, let that one sink in - is the backstory that has been done is actually pretty damn good. The New Republic’s only flaw was its forgiveness and idealism. The response to that, from some fans, is to argue for a Starship Troopers hardline approach that misses the point completely.
If you go with the idea that the PT is the galaxy’s descent into darkness and the OT is how the galaxy is gotten out of it, it’s not unreasonable to think there should have been some sort of progression from the ending of Jedi and not an OT redux.
In the end, this is all academic, it’s done now.
What’s kind of a shame is how the ST films tend to overshadow everything else because I’ve really enjoyed that other stuff - the books, the comics, the animation, Rogue One - Donnie Yen in a SW movie, hell yes! - the little links between them that have been made. They even tried to follow through on the logical consequences of the Clone Wars and almost succeeded.
Getting back to the Marvel-SW film comparison discussion I think the difference is simple: SW sees fans as disposable - lose one and two new ones will take their place - and it’s probably a pretty accurate, albeit cynical calculation - Marvel does not.