What chiefchirpa just said in regards to sequels is indeed true, however, i think Marvel should take a chance and just keep it during WW2.
Hear me out;
I think the dynamic of a "man out of time" is very cool, but in order for it to have any serious impact...in order for the audience to really FEEL for Steve Rogers and all he's lost....it has to be developed slowly. We have to see Steve's relationship with is family and girlfriend....his comraderie with Sgt. Fury and Bucky Barnes....as well as tell his origin and introduce his enemies.
I realize that superhero films set in this era tend to, well, suck, but for every Phantom and Rocketeer, there's an Indiana Jones and Road To Perdition. The key is in the casting, and the script. Like the Indiana Jones movies, Captain America should be action-packed, humorous, and clever...but serious intense, and kick-ass when it needs to be. The director needs to keep the budget low to help ENSURE a sequel is green-lighted....but then, maybe a direct sequel isnt even needed (see below).
The final scene of the movie should be Cap & Bucky jumping on their motorcycle, and riding off to stop Baron Zemo's rocket from launching towards Washington D.C.,...
The sequel should then focus on the "man out of time" stuff, with Cap getting frozen, Bucky (apparently) dying, then Cap waking up in the present. Perhaps in an Avengers movie. Scenes with Cap visiting the graves of his family and old friends...and his now elderly former lover refusing to see him, will definitely tug at the audiences heart strings...
So yeah, im definitely a proponent of them taking a cue from Sam Raimi, and developing the plot somewhat slowly, for more emotional impact.