Your first paragraph is what I meant. You said it better. Brooklyn will demand more than JB, Theis and a first. It will be JB plus Marcus or White plus all of the picks.I think there is a good case the Nets want more than the Celtics are giving.
Salary isn't a major concern unless people are real torn up about adding Theis.
I will say though, sure Durant may want out in 2 years... but Jaylen can walk for nothing in 2 years. He 100% isn't signing an extension for financial reasons, so there is actually a much higher chance of losing Jaylen for nothing in 2 years, where Durant you can recoup assets with 2 years left on his deal if he wants out.
Yes, JB can leave, but KD is a flake and a huge star. He's averaging 2.5 years per chosen destination lately.
Edit: covers response to Ed too