If the Dursleys are gone, I'm going to miss them. They are the worst sort of muggles--the kind you love to hate. They prey on small defenseless people. That's the reason that Harry Potter wants to slay evildoers. He's making up for all those years he couldn't defend himself against the Dursleys.

The thing about Peeves is that, as a character, he doesn't move the story along. He's good for a few laughs but that's about it. So I don't think Peeves will be missed in the movie.