As the undisputed "faces" of the MCU now that they've pretty much concluded Tony and Steve's story arc in Endgame?
https://moviechat.org/tt4154796/Avengers-Endgame/5ce5ba81014be45ed164fb87/MCU-next-big-three-Marvel-Trinity
That is probably a very loaded question to answer even for Disney.
Neither Downey nor Evans were anointed or appointed as the faces of Marvel/Disney. The characters reached those positions through historic representation over 1000's of books in print and the MCU lucked out with RDJ. I would suggest to you that if Marvel had it's way they would have started with the Fantastic Four as the model because of First Family were indeed the face for Marvel in the beginning.
Spider-Man, Black Panther, Captain Marvel are the nascent new faces. It will take time. Captain America was shunned early on in the MCU and Captain America:The First Avenger was NOT well received and even Whedon seemed to treat Cap as an afterthought in the Avengers, and more as a joke to Stark's punchline. Even Thor wasn't treated too regally by Whedon.
The Russos really did the MCU a huge favor by really addressing Captain America; and Evans was a willing and committed actor to pull off a tough assignment.
Marvel has it right in that for them it is about Character. The stories are all there they still just need to focus on Characters and Actors that can both inhabit and bring those characters to life while stamping them as their own.
Black Panther has charisma. Captain Marvel is mega-powerful. They need a Spider-Man reboot though.
First Avenger was very well reviewed. And they made Cap the battle leader against the Chitauri when the stuff hit the fan.