Technically, yes they are who they are and everyone knows that, but there's still a couple things they can do to boost their trade value.
Zach will always have his boneheaded plays, but again this is already known. He needs to show he can drop 25+ any given night on good shooting efficiency with consistency and he needs to show he can stay healthy.
Vuc is who he is, but if he can get his 3pt shooting back to a respectable number instead of the awful numbers we've seen the last two years, some team might take him for the offense/rebounding. For some reason the Warriors keep coming to mind.
The Bulls beat writers will all cite the new tax apron rules as reasons why we won't see either player moved during the season (fair statement as most contenders are over both aprons and cannot send multiple players out in a trade nor can they take back more salary than they send), but if they can put together a full season doing the above, there should be buyers come the offseason.