Just about the only exception right now is Ms. Marvel, and even then she never "replaced" Carol.
And that's exactly what happened.
Jane Foster? Sidelined, gets the Valkyrie title as a consolation. Probably won't last a year.
Sam Wilson? Yeah, Cap's not old or a Nazi anymore so he's gonna need that shield back. Chop chop.
That's the kiss of death. You get sent off to live with the West Coast Avengers or something and then fade into the background.
You become "lore."
But the movies *have* to, what with the realities of actors aging or moving on. So Spider-Man Far From Home is going somewhere the books never dared, and it's for keeps.
He sort of has a circle of protection drawn around him, in that a large part of his audience sees themself in him. His movie killed.
But that only lasts as long as his popularity and visibility.
Except he's too popular.
Unless it was written before 1979. Then it never dies. Never ever. Even if it actually dies.
Comics hit arrested development at the end of the Silver Age.
"But I've been the Flash for 20 years! Through four Presidents, even."
"Hmm? You're still here? Oh, I'm gonna need the costume back. Drop it at dry cleaning on the way out, yeah?"
The Justice League cartoon. For a whole generation of kids, he was the only Flash they ever knew. It protected him.
For a little while.
Only a little while.
Every medium has its level of how stuff "really works," but comics barely has the ideal anymore. The crap's too visible.
Fuck's sake, Grant Morrison got Batman and immediately put a gun in his hand.
That got undone because it fucked status quo.
After that the annual events spiraled out of control.
Those were the big events that revived comics (a little) after the speculator crash.
So both companies drove it into the ground.
Marvel's done THREE Asgard annual events in ten years, ffs.
Shit like that completely derailed Spider-Gwen.
To bring him back, a villain sucked up all his energy into her son until his hideously bloated carcass turned into Proteus.
He was vulnerable to metal. He died again.
Huge derailing crossover.