Captain America and the actor is actually one of the most loved character from Marvel Cinematic Universe. For sure, a lot fans will miss him.
However, Chris Evans, as well as the other actors portaying the other MCU characters, are not getting younger. Their appearance will change, and that can affect their respective performances of the characters. We cannot even say what's the future of MCU. Are they going to make a major changes on the characters, perhaps a reboot of the whole MCU?