Do something completely different. What, I don't know, I'm sure they already have plans, but you have to do something different than "giant epic fighting crossover with macguffins". Secret Wars or Secret Invasion both seem meaty enough (technically Secret Wars is a big fighting crossover but it's entirely different from the Infinity Wars type of fight) , but I don't think you'll see a traditional Avengers teamup film for a long while. Nor should you really, the solo films are just as huge now (two billion dollar ones in the last year) and their "soft" crossovers like Thor Ragnarok featuring Hulk, Spider-Man Homecoming featuring Iron Man, and potentially GOTG Vol 3 featuring Thor, are a good idea.
There is no rush, at all, though. They have further solo films for the current roster (GOTG, Strange, Panther, Ant-Man, Marvel) to do, new characters they're already moving like Eternals, Shang-Chi, etc, and of course, they just got back FF and X-Men, both their own massive rosters of characters. They've already shown they can take B listers, C listers and even D listers and make them top tier blockbuster brands. The second generation of the MCU can go anywhere they want.