The Blazers would do this if...they admit that they only signed Grant to a long-term deal because they thought Damian Lillard was part of the team's future. Now, as a rebuilding team, they don't need an oldert player on a high-dollar deal. The salary cap relief in this deal is significant. Hayes and Morris come off the books this year, and Holmes gives them a mid-size expiring contract that they can use in a deal next year. Four second round picks doesn't sound as good as getting first round picks in the deal, but it's appropriate due to the nature of Grant's contract.
The Mavericks would do it if...they're okay committing a sizeable piece of the salary cap to Grant, given that they might want to make another big move over the summer when they have access to more of their first round picks. Assuming they make another deal for a high-level starter, can they really pay big money to each of their top four players?
The Pistons would do it if...they like O-Max and see him as a potential building block moving forward. Would they rather have O-Max or have even more money to spend this summer when Hayes's contract expires? This deal could be simplified by removing the Pistons and sending O-Max and Curry directly to the Blazers, but the Blazers might not want O-Max since they drafted Kris Murray and Rayan Rupert last year. The Blazers would likely prefer the second round picks from Detroit.