People didn't get fatigued with Star Trek because there were too many shows or movies. People got fatigued with Star Trek because the shows and movies declined in quality.
That’s rather subjective, and I feel it’s because of the constant churning out of Trek media in such a short time period that writers were spread thin, studios wanted to play it safe with returns, and this the show suffered. By Trek’s end (late Voyager, Enterprise and Nemesis) it was churning out bland and mediocre stories. And thus the general public grew weary. Whether it was because they couldn’t keep up or because of quality decline from too much Trek cant be stated definitely.
Marvel releases three movies a year, on top of multiple ongoing TV shows spread across several different networks, and people are clearly not fatigued with them. They won't become fatigued with Star Wars just because they're putting out one movie a year plus an animated TV show (and eventually a live action one).
Apples and oranges; Marvel already had a vast, rich universe for material to pull from and had dozens of recognizable characters and villains to build a cinematic universe. They also have literally been attempting something-never done before, with 70 years of material to pull from that many have literally waited decades to see on screen.
Disney is literally working a blank slate besides the first six movies, as their “vast rich universe” the EU, was wiped out. For many reasons, most of them agreeable to me. It needed to be done. But that means they started from scratch in some ways. One might say that Disney could do the same as Marvel by pulling stories from EU novels and rebooting them; but many disagree saying the casual fans can’t follow that; yet that’s exactly what Marvel is doing; they take comic book fans favorite arcs (see for instance Civil War), some that casual fans may never have even heard of (see Extremis for example; I never knew about that arc before IM3) and then adapt them and retool them to make them box office friendly.
I also think MCU is lightning in a bottle, one of them being is that somehow they’ve produced mostly quality films with real few dogs, if any at all. I rarely see dissension for MCU films, mostly acclaim.
Star Wars meanwhile has had quite a divided reaction from the fan base and just like you argued that a decline in quality was the reason for Trek’s hiatus, could it be the same for Star Wars if that happens? Depends on who you ask. But if Solo diminishes in returns, I’ll be very interested to see the box office for Episode IX next year.
