I always liked Nishi, he was crude and honest in the way we don't like honesty (when truth hurts). When he gave his "speech" in the beginning of the second mission (when he told the truth of all the other gantzers) I was completely shocked, no "socially" aceptable person could do something like that. I think that's where he his "badassness" is, his crude way of referring to others, but I don't think that he's going to keep it now, since the other gantzers aren't really newbies.
I don't think he'll become soft and supportive either, he'll be almost the same.
I hope Nishi doesn't lose his edge. Thats what makes him special. I know when I say that rant of his.. my gawd I was sold. Even though he died crying. Reminds me of Vegeta from DBZ. Crys.. dies.. and comes back. XD