On one hand they’ve got this one in a million situation: Matthews and Marner have one year each left on criminally cheap contracts relative to their skill and the Salary Cap. Therefore this allows the Toronto Maple Leafs to get a ton of extra cap room this season that they’ll never have again.
In addition, it’s not like Tavares is in decline, but he’s 27 and smack dab in the middle of his prime. Matthews on the other hand is is 21 and entering his third season. Enough players have had their best ever year in their third season that it’s a reasonable possibility that the Matthews/Tavares combo could be the best it will ever be right now.