I don't think he will be? Also I think this is completely separate from the Prometheus films, although the Engineers were mentioned in one of the articles I read about it. (They are the same universe, but completely different timelines and stories, so I'm not sure how they'd fit together.)
I am excited about this. I love Aliens the most in the series (closely followed by Alien) and while I really do like Alien 3, it did kill off my favorite characters. Like...all of them. And Resurrection was a ugly mess of a movie, I'm pretty sure everyone agrees on that point. From what I saw of the concept art, it looks really interesting. I'm hoping Michael Biehn will come back and be Hicks, as the character is in the concept art.