I don't think he has trade value. He's an aging RB locked into a meh contract. Plus, there are better backs available. Like Aaron Jones. I would release/trade Montgomery and pick up Jones.
They don't have many they can release to clear cap space. Decker was the biggest one. They do save some if they release Montgomery. Glasgow is likely gone and will save some. That is about it. Most of their players are on recent second contracts or rookie contracts.