Feige reiterated, recently, that Endgame is really about the Original 6. Captain Marvel isn't just going to show up and steal the show (thankfully).
Marvel doesn't always get everything right, and neither do the Russo Bros (Civil War isn't a great movie IMO), but after seeing Infinity War... After all of that hype... And not even thinking how it could live up to it... And then blew that hype out of the water... They have a lot of good will - but now even more hype. I don't know how they're gonna pull it off.
If they stick mainly to the guys that lived through the Battle of NY, through Tony's Ultron experiment to help defend mankind, etc. That's the way to go. They're the one's that started it all and have the most attachment.