What struck me most about the trailer (apart from the most awesome Winter Soldier and him going hand to hand against Cap) is the morality displayed in the trailer (and hopefully in the movie).
I'm not a big Cap fan way back when i read comics on a regular basis but he always embodied a simple, uncompromising black and white view of the world. He knew what's wrong and he didn't make concessions or soften it up around the edges if "times demanded different actions".
He just was this fixed point where you could measure yourself against to see how far you have strayed. Some may call that simplistic but it's also the greatness of the character who won't budge under any circumstances and who will face every consequence but he will remain true to himself.
I guess if he were real and live in the post 9/11 world he would have some choice words on Guantanamo, Abu Ghraib, the "Patriot Act", wiretapping etc (heck.. he even quit the job at one point in the comics out of protest because he couldn't support the government's actions).
If that translates well into the movie i'll be one really satisfied customer, if not at least i'll get some cool scenes and 'splosions for two hours.
I definitely agree with you and I do believe that this is exactly what is playing out. Based on what we have seen in the trailer, I think we can gleam some of that.
It looks like he starts out in the SHIELD "patriot" uniform. After the Winter Soldier attack and Nick Fury being hurt, he discovers something about SHIELD to cause him to abandoned that SHIELD "patriot" uniform and break into the Captain America museum and retrieve his old Captain America uniform at the end. I think Captain America will break his ties to SHIELD in this movie and put SHIELD into disarray.