Kings are not taking that cap dump, even with the first thrown in.

fair enough but he's good enough to not be considered a cap dump.

The Kings are not going to be contending for the cup this year. Why take on additional salary, especially when there are no fans in the building to help get revenue in. Unless it's a deal you can't pass up I don't see the Kings doing any more trades until the trade deadline.

McDonagh won't be that hard to move.
They might get a return on him, probably a decent one.

They get Roy

yeah but LA is not the team making this move. They are in rebuild mode. That team is shot, they aren't moving out younger guys.
They are getting out of those 3 aging forward contracts and moving on.