I mean if it comes down to franchises, the reality is that most franchises are tired or played out..., what will happen to Star Wars in 10 years? What will happen to Marvel post-Infinity Wars when RDJ walks away?
Of course, those franchises won't die, but there will be serious fatigue, just as there is in Disney's own Pirates of the Caribbean. Harry Potter's Fantastic Beasts movies aren't quite as strong as the main series.
Disney itself isn't immune to franchise fatigue, it's just that they were smart to realize that Marvel and Lucasfilm had 2 major franchises/universes that hadn't been exploited in a significant fashion yet. The MCU works because it's a clean/fresh script that could be filled by RDJ and the rest. That won't be the case for the post-Thanos phases which will operate in a world where it's "already been done" and they're trying to carry a weighty franchise forward. A lot of the reason why things like GotG or Doctor Strange work is that they feel fresh compared to previous superhero movies.
That's one of the main reasons why the DCEU has largely failed... because Superman and Batman in particular have already received a large number of live action films and coming off of the Nolan trilogy, it was going to be hard to have that same impact with a new batman. They could only sell the "ensemble" idea one time before Justice League came and flopped. Sure they should have done a much better job of building up the universe with more introductory movies for Flash and Aquaman even before Batman vs Superman, but we'll have to see how well superhero movies hold up in the longer run once the first set of Avengers retires.
Rebooting X-Men isn't guaranteed to be successful either; I think it will work at some level to plug the hole of heroes leaving, but Fox has exploited that series pretty heavily the past 20 years and will go out with a last hurrah of a bunch of movies this upcoming year. Disney will have to be careful to weave it in in an interesting way similar to Spiderman Homecoming.
All of that said, franchises still have long-term value like Spiderman or James Bond or others. They can still be carried forward, but there's never a guarantee, that's a part of the reason why Fox is getting out of the business.
Universal's best shot at a major new franchise in the mid/longer run is these Nintendo rights if they can make that animated movie a big hit.