I don't want to beat a dead horse to the point where everyone else here is banging their heads against a wall. But I'll take one more stab at this before I move on.
Let me reiterate that I liked the first two Terminator movies just fine. They are both very good for what they are (a low-budget cult movie and a big budget actionpalooza). T3's not good, but it's watchable. This is where the repetition really begins to wear thin. Salvation at least attempted to do something new, but that's about all it had going for it. The execution was really poor on that one. Genisys tried to have its cake and eat it too with a reboot/sequel hybrid that disappointed most. I have heard Dark Fate isn't much better. It gets back to the original cast, but doesn't have anything new to say.
Your franchise summaries are comically broad. Yes, all the HP movies involve wizards and all the F&F movies have action scenes. That doesn't make them functionally copies of one another. Watch one of the Christopher Columbus Potters and compare it to one of the later entries in the franchise. They are radically different beasts.
Most sequels are unnecessary. It's especially hard to make a sequel to something like Jurassic Park because the premise has a problem baked into it. Why would anyone ever go back to the island? All of the JP sequels have struggled with this issue and I would argue that none of them have ever overcome it. Harry Potter and Fast & Furious are more open to sequels. Our heroes can have multiple adventures.
The Terminator also has a limiting premise. The entire story is told in the first movie. We know everything we need to know about this world by the time the credits roll. There's not a lot of drama left in the war between man and machines when you know going in how it's going to end. The heroic John Connor will lead humanity to victory. If you deviate from that, you're not really making a Terminator movie anymore. Might as well call it something else. But if you stick to it, you're very limited in the stories you can tell.
Cameron seemed to be aware of that which is why he basically retold the same story in T2 but with bigger action and special effects. Audiences watching the revolutionary CGI in T2 weren't all that concerned that Cameron was hitting the same story beats. The action scenes were next level. Very few sci-fi action movies, Terminator or otherwise, could touch what Cameron did with T2. Which is why Schwarzenegger's career suffered post T2 and why Cameron never revisited the series. There's no story left to tell.
People have argued with me that you could tell stories about the post-apocalyptic period before humanity's ultimate victory. You can, but why? We know the outcome already. You'd be better off setting your story in a new world which isn't constrained by Cameron's prophesy. He doesn't have a copyright on killer robots. Do something new. You could also set a story after the machines are defeated, but again, why not just do something original at that point?
Most of this more relevant to the movie franchise itself than it is to Universal theme parks. The best fit for a theme park attraction is more complicated than the subjective quality of the source material and its ability to generate infinite sequels. For example, no movie series is as evergreen as James Bond, but it would be challenging to build a 007-themed land.
I started this conversation by suggesting that Terminator probably isn't as relevant as a lot of its diehard fans think it is. The soft box office performance of Dark Fate this weekend supports my argument. Once you get past the people who grew up on the original movies, it doesn't have a lot of devotees.
They have to work within the existing footprint. That building couldn't house a dark ride. It was built for a show.
Terminator is a part of pop culture in many ways, and it made sense as an attraction of some sort. I think it could’ve lasted longer if it was a ride, or an interactive land akin to Galaxy’s Edge where guests go forward in time to fight the Future Machine War.
