Even with Embiid likely out for the season, Philadelphia isn't likely to retain Tobias and the theoretical cap space they'd have by letting his contract expire would give them enough money to sign... Demar Derozan? So instead of waiting for the offseason and making that swap, they send Harris + assets to Chicago to aquire not only Demar (who can play the 4 and is an upgrade over Tobias) but also an All-Defensive guard and a realiable 3&D vet.