The leverage is owning the rights to the biggest comic book character in the world.
With the sobbering realisation of failure, an opportunity presents itself to reset and go after the best talent in the industry to turn it around, something Marvel Studios would never do with Feige around.
I agree they squandered it, but that's because the people behind the scenes are even less impressive than Feige and his lame counsel.
If they see this as an opportunity, they could turn it all around in short order.
Of course this is best case optimism, but the alternative is continuing the dance of mediocrity since it started in 2017.