Chris Evans Returns As Captain America In Avengers: Doomsday... Why?

Chris Evans is coming back to the MCU for Avengers: Doomsday. He joins Robert Downey Jr. in some capacity. We have no idea what his role is but I'm going to take some time to speculate over this for fun. The Captain America title has been transferred since Steve Rogers got super old. Now he's somehow returning to either fight as an elderly man or play a different character entirely. What in the world is Marvel/Disney smoking these days?