They haven’t come close to “using up” 60 years of comics.
They just stopped focusing on the market for super hero movies — teen boys and thinking people want to see two nasty unpleasant ugly lesbians and a fat ugly muslim girl as a super hero team — aka thr Marvels.
Not what I’d volunteer to watch as a kid.
There aren’t 60 years of good stories. Most comic books, unless they’ve been planning a story for years on end, tend to be crap. There are only two big stories in Marvel, that I’m aware of, that they haven’t touched on. The House of M and The Secret Wars. However, they’ve used up everything else.
You’re right that they went to the left, whether or not their fanbase wanted it.
I’m personally all Marveled out because of what they’ve done.