I have 0 interest in McCollum, just mentioning his contract. It's really ugly. I wouldn't even trade Knight for him straight up, and the Blazers might consider that because of how much they'd save. Knight comes off the books 1 year before McCollum and makes half of what McCollum does annually. They're at the tax line right now and they'll need to pay tax to retain Nurkic.
The Blazers are in salary hell right now, that's why people think they'll blow it up. McCollum isn't their worst deal, not even close IMO. Meyers Leonard is making $31 million over the next 3 years, Mo Harkless making about $34 million over the next 3 years, and Evan Turner making $38 million over the next 2 years. They have Nurkic, Shabazz Napier, Ed Davis, Wade Baldwin, and Pat Coughnaton all as free agents. They can only afford to bring 1 back at around $10 million a year before they get into the luxury tax.