The studio has already announced that Captain America 2 will be set in the present day, which is too bad, because I would have liked to see another WW II adventure tale. So here are my thoughts.
In the sequel set in the present day, the film should try to deal with the fact that Cap is a man out of time. One of the things that The Ultimates as written by Mark Millar did well was to address what that meant. In the comics, one of the characters Sharon Carter, was the relative of Peggy Carter, who Atwell played in the film. I would be interested to see that relationship on screen handled with the maturity that the first film managed.
Of course I’d really be interested to watch a sequel that was set during WW II and would take place sometime during the events of the first film. I picture it like a Bond film with a lengthy opening sequence and then the rest of the film is a single complicated mission with Agent Carter stuck in the field a little longer than planned. I think of a film like Where Eagles Dare (a great flick if you haven’t seen it starring Sir Richard Burton and Clint Eastwood) but there is a whole school of films set during the war which aren’t light-hearted per se, but aren’t realistic takes on the conflict.
Another option is to give the Howling Commandos their own film. Bring back Atwell and Tommy Lee Jones and send the team off on missions. Have Dominic Cooper as Howard Stark play Q. In the comics they were led by Sgt. Nick Fury (who later ran SHIELD). Obviously that won’t work, but it might be interesting to bring in a character of Sgt. Fury to lead the team after Captain America was killed. It might be interesting to watch a white man who has back home an African-American wife and is the grandfather to Sam Jackson’s Nick Fury.
I mean for Cap, the filmmakers assembled a great group of actors including Neal McDonough and Derek Luke. Might as well put such a great troupe of actors to good use. And to do it in a summer action movie that a kid could see with their parents or their grandparents would be something no one else is doing, but Cap showed that there is a market for such a film.