I like Hawkeye, I like Renner, and I hope they keep him around. I certainly hope they don't kill anybody, thats one thing I've always hated about comics. Why kill off characters? I read comics FOR the characters, to see them in action, interact, and to follow their stories as they unfold.
Having said that, if someone dies in AoU my money is on some less central characters, such as War Machine, Pepper Pots, or even a bunch of random civilians, (which would make sense considering that was really the catalyst for the super human registration act in the comics)
Think about that. Ultron wants to wipe out humanity, who says one of our beloved heroes will die and not a bunch of innocent civilians. That is guilt enough for Stark to spearhead the registration as well as cause further rift between him and Cap.
If anything happens to our heroes I dont think it will necessarily be death. There is the rumor of Hulk/Banner being blasted into space. There is the possibility of something happening to Thor as well, considering the title of his third film, Ragnarok (which I sincerely hope deals with Thanos or his minions attacking Asgard to get their hands on Infinity Stones).
Futher more, I dont think Quicksilver will bite it either. Just because he is not seen in the BRIEF final battle shot we saw in the trailer doesnt mean he isnt there. He has super speed, he could be running around somewhere so fast we cant see him, or perhaps he is on some other side mission that requires his speed. It looks to me like they are defending something in the middle there, perhaps trying to make time for Quicksilver to accomplish whatever his mission is.
Further more, I think Quicksilver and Scarlet With will be our POV for the Inhumans film, considering they are rumored to be Inhumas as opposed to mutants, and considering Quicksilvers relationship and interactions with the Inhumans in the comics.
All I know is I want a scene of Cap, Hawkeys, Quicksilver, and Scarlet With in action together in this movie, an homage to "Caps quirky quartet" from the comics.