Sony and Fox (especially Sony) will have nothing by the time the next decade begins. Spidey will always be an option but they're going to kill it and need a long break. Marvel needs to survive as a studio, so they'll keep em' coming but the numbers will go down, people will be exhausted. Ideas? I dont know about you but i dont see Thor movies, Cap movies, being made once that last movie hits with Thanos. A lot of the smaller characters will have their films going until the early part of the 2020's, but even that won't last too long. There's only so much you can do once these actors bail out. An Avengers 4 will probably happen but with a younger group, and so i dont think that's going to be the hit they think it's going to be.
The genre won't crash and die for several years. But it will be on life-support for a while. Audience exhaustion coupled with writers block. I'll bet anything on it in 10 years time. Marvel & DC are blowing their load so to speak all at once, in the span of 6 years. Without thinking of the future.
The Batfleck movies may make crazy dough. Or it won't be well received. Chances are it will be praised by all. Loved. But it will have an ending once Affleck bails. And so they have the option to do prequels, reboot once again (may as well call them prequels no?), or go back to a past Bat-actor. What's the best for business? I think prequels could work but i think that strangles the actor in the role with constant comparisons to the older Affleck. I personally don't like the idea anymore. The reboot, in a new stand-alone universe, with a younger Batman is going to happen again eventually. Probably in a horror looking Gotham. But it's the worst idea ever to do this directly after Affleck. You'll have some fans rolling their eyes "jesus christ, they're announcing ANOTHER REBOOT? How many reboots is this now? Three?". Push that back. Let WB indulge in an older Bruce from the past like Keaton or Bale for a Batman Beyond. Something along those lines. Then after a while of not getting Bruce as Batman in the movie world, people will be begging for a younger Bruce who is BATMAN.
Another thing, is we're all assuming every Justice League and solo movie from DC will be a hit. A lot of these solo movies may straight up bomb. Justice League, as a sequel, has potential to do great or just "decent" numbers. If they take it into a third film, it could bomb if they don't have key players like Batman or Superman involved much.