after enough time people will start to long for what made the franchise in the first place.
If you want to look at it like that, then: TOS reruns, the first four movies, TNG on TV, and the Abrams Films.
The End. Without those four, the franchise as we currently know it isn't possible.
TAS, Movies 5-10, DS9, VOY, ENT, DSC, PIC, LD, and
Short Treks are secondary in importance when it comes to the overall existence of The Franchise. Not the same as "not important", but secondary nonetheless.
EDITED TO ADD: Bear in mind, I just called a good amount of what I like "secondary", so this isn't based on my tastes. It's based on my reading of the history of Star Trek.
Without TOS's success in reruns, it doesn't return as a film series. Without those first four films proving Star Trek can be more than just a show from the '60s, you don't have demand to bring it back as a show for the '80s in the form of TNG. Without TNG, you don't have DS9, VOY, and ENT. Without the Abrams Films, you don't have evidence Star Trek can be brought back from the dead, and then you don't have any of the Streaming Series.