They did it before. But it's likely whichever actors are involved in 5 and Secret Wars, will simply have to turn down a lot of projects and backburner some passion projects for the next 2-3 years like what I would think the Infinity War and Endgame casts had to. Another question is are they going to be fairly compensated for doing so?To be honest there are enough characters in the wind for a large team but then that begs the question of how you manage actors' schedules, writing, bringing them all together and making them work as a team, etc.