If he demands a trade with 1 year left on the deal, it puts the Blazers in a position where they get very little for him because a few destination teams know they can just get him in Free Agency if they wait a year.

With 4 years left on the deal, the Blazers at least have a long-term contract to trade with a significantly larger pool of eligible trade candidates and will likely get a lot of value out of it, even if that value is in the form of rebuilding assets. You are never going to be able to get the same value out of a trade when you trade a superstar like Dame, but I would have a hard time hating Dame as a Portland fan under the circumstances.