In his prime he played around 77 games/year and got around 47.4 wins/year for Portland, playoffs every year...
This is the second consecutive year he's going well below that 77 games, second consecutive year they are missing the playoffs. The reality is Dame, like other older stars around The League, is declining, and the tell isn't to look so much at his play. Like Durant, he's still crazy productive when he plays...
The tell is to look at the increase in injuries and missed time for a guy who was 77 a year over an 8 year stretch. Dame is a declining player and it's time to move on...
If you're the Blazers you could keep him if you think you could put the appropriate pieces around him, sure. But it's probably a lot easier to just rip the shyt down to the studs, the haul you'll get for Dame will accelerate your rebuild. Echoing others, it's best for both parties. Find out a list of preferred destinations for him, and this summer work on negotiating among that list to get him outta here...