Depends on what you get back in a trade for him.
If you think removing Matthews from the team is addition by subtraction you're wrong. This isn't Jacob Trouba we're talking about. Despite their winning record with him out of the lineup the Leafs are definitely a much better team with Matthews than without.
A stud franchise centre is an absolute must, must, must have to win the cup.
They might not win with Matthews but they definitely won't win without him. There is no overstating just how important Auston Matthews is to this organization as a result. He is the Captain of the team and face of the franchise.
He is literally re-writing the history books in front of our eyes.
If, for some ungodly reason, the Leafs decide to trade Matthews they may as well just start the rebuild. Because even if another #1C were to come back he would be a lesser player than Matthews. Teams aren't gonna let the Leafs rip them off so the throw-ins wouldn't be enough to improve Toronto over status quo.
It's pretty hard to imagine any scenario where this team would be better off long term without Matthews than with him.