Its going end up being Schroder to the cavs into the DPE they got for Rubio. The cavs will send back a minimum salary or two in order to avoid going into the tax, one of which probably gets routed to OKC with cash to clear the salary. The Celtics will get one of their good 2nd rounders (they have HOU and SAS 2nd's this year).
Celtics lose enough money to duck tax and get a 2nd rounder.
Cavs get a good player, avoid going over tax.
Makes a lot of sense for both sides.