I know this isn't the greatest trade ever...but it does address some needs for the teams.
Hawks get draft capital to use in helping get players to work alongside Young.
Magic get a true center who will be able to play alongside one of the three bugs they could choose with the 1st pick. They also get Johnson who helps with scoring at the wing. Langford and the 38th are filled, and could be used to package for other players...or to help trade away Ross.
Spurs get a big who can stretch the floor, and a defensive minded combo forward in Okeke. They use the 9th pick on Duren, and the Hawks near lottery pick on a player like Eason, Dieng or Sochan. That covers any lack of D that Carter brings. Then with the early 30s pick they get a solid wing scorer.
Does it make any team great? No...but it probably makes them better than they are now.