Nuggets: get the go-to scorer they need. As good as Nikola Jokic is, you cant rely on him 100% of the time. If this trade happens the Nuggets can be legit title contenders.
Wizards: If they are concerned about John Wall coming back from his injury, they do this. If they think he will be back to his old self, they make a push to win now. If they decide to blow their team up, this is a good trade for them. They can build around a young and talented forward in Michael Porter Jr, while also bringing in Gary Harris, and 2 extra first round draft selections.