I think the mavs want to keep butler around because of his presence for the rest of the year. honestly I don't think they would trade him unless they had a multiplayer deal that included a significant upgrade, but he is old and a knee injury at that age might continue to hamper him.
I just saw an espn headline calling for nash to be traded. the mavs lack dribble penetration in the halfcourt from their guards(especially with beaubois out). while j-kidd is great defensively and in transition...and is great setting his feet. nash does everything offensively. would the suns/mavs consider a deal for nash? the mavs would give up a lot defensively because j-kidd does a lot at that end. i would think they would have to keep kidd. this is pie in the sky, but could kidd and nash play together on the same roster?