As it is with all things regarding this team - it depends. If an honest-to-goodness franchise player, like Paul George or Jimmy Butler, shakes loose then you give a hard look at what the other team is asking for. Otherwise you look for a buy-low opportunity on guys who might help you this year but don't necessarily make you a contender. No interest in moving a Nets pick for Millsap, who I think the team is well-positioned to pursue as a FA over the summer, but I'd give them a combination platter of Olynyk, Rozier, and non-premium first-round picks. I don't expect Atlanta to take a deal like that, so I don't expect Millsap in green this spring. Otherwise, to echo what a few other people have said, I wouldn't mind turning Zeller and a second rounder or two into Bogut, who would come in handy if Boston runs into Dwight Howard or Jonas Valanciunas (or Robin Lopez, for that matter) this postseason.
Sneaky-devious trade target: Brook Lopez, using the 2019 Minny pick and some combination of the C's own picks and the Clippers' pick, which serves the dual purpose of getting Horford a frontcourt partner (who also stretches the floor now!) while making the Nets even worse over the remainder of this season and next.