The Spurs' flexibility in trades is greater than most
In regard to potential trades, San Antonio will have major cap space, and their ability to take back big contracts this summer makes potential deals much easier. Still, their ability to do so will depend on whether the other team has the assets needed to make it worth the Spurs' while.
One option could be to package McDermott with Josh Richardson to a team that needs an upgrade, has bad contracts, and has enough tradeable assets. Or they could keep it simple and shop him separately, with several suitors likely to pursue him. That would obviously be great for the Spurs and increase the chances of them receiving an excellent return for McDermott.
Who knows? In addition to getting a 1st round pick back, they could also receive another flippable player they can later move for more assets. With the Spurs in a rebuild, acquiring and stockpiling picks is an important aspect of it. They've done a great job so far, but if the team isn't likely to make the playoffs in the immediate future, then moving a win-now player could help them when they are.
Ultimately, San Antonio should consider trading McDermott this summer, especially if they draft a power forward. If they do select a four, then he'd become expendable and the Spurs could receive a first-round pick if they move him. McDermott is definitely an offseason trade candidate worth exploring.