He would also return a king's ransom but he's also their most important player in terms of position alone, so they definitely shouldn't be trading him for a top-"10" prospect of choice + a bunch of lottery tickets. Their checklist should include: getting a (potential) 1RHD, a top 6 player, having C stability, and having enough goal-scoring.
Matthews is from Arizona not Utah, so he won't waive to go there. Leafs struggled to score in the playoffs this trade makes that situation worse. And as above comment stated, it doesn't address big needs on this team especially a 1RHD plus a top 6 to replace him. Fingers cross Tavares or Marner waives it