Captain America

Sebastian Stan’s Bucky Barnes is slowly being nurtured into replacing Chris Evans’ Steve Rogers as the Marvel Cinematic Universe version of Captain America – and that will probably happen after the Infinity War movies.
It will be a move triggered by the likely death of Evans’ Captain America – and that death could come with Cap making the ultimate sacrifice to defeat Thanos and save the universe.
In the Infinty Gauntlet comic book arc, Captain America was killed in an iconic scene in which he stood up to the Mad Titan on his own – bravely but foolishly – in spite of the villain essentially being God at the time.
The same thing could happen in the MCU, but this time Cap’s bravery could somehow result in both him and Thanos dying – and what a fitting way it would be for the most courageous and virtuous character of the franchise to bow out.
