Few franchises that span generations?

The entire current zeitgeist of popular media is about zombifying your parent's IP. It's Nintendo's entire business in fact. Sure, usually they are doing good work with that IP, but they are the outlier in the industry. Everyone else is shitting out remakes of what your daddy played that don't even understand the original material, or like Halo, remakes of what your daddy played which was already a mediocre remake.

Halo 1 came out the month after 9/11. It's old enough to have graduated college and started a family. It will be resold soon.

Jurassic Park was dug up out of the grave to crap out several more movies. Star Wars is inflating a couple good plot lines into an entire Universe of "Content". Even reality shows are made up of people who were contestants on older reality shows. Pixar is making yet another Toy Story.

Aliens is still going, long after it's reanimated corpse was overplayed.

One of the premier television series, that just finished, was all about nostalgia for living in the 80s, with some silly plot tacked on that apparently even the writers didn't care about.

Even our propaganda, like Top Gun, is basically the same script as an 80s movie with minimal changes.

It feels like the entire media ecosystem is designed around reselling content to my parent's generation before they finally kick the bucket or satisfying the nostalgia of that generation's early children. Even the President's administration bitches about things like the 90s USDA food pyramid that only affected that 13ish year segment of the population and was deprecated, twice, since then. Our authoritarianism is nostalgia based, for the time that generation was children, and things were "Simple" and "Good", because they were children and got to live the lives of kids.

Maybe I should have qualified it with "successfully" span generations. I think most of the examples you give could be better explained as Member Berries, but I agree with the sentiment. I just don't think kids are as interesting in Halo, Jurassic Park, Star Wars, etc as we were - despite incredibly heavy handed pushes from studios.