News of a team's star player missing time because of an injury isn't ideal for any fan. But, in the Leafs' case, Leafs Nation has seen a number of solid players sidelined this season and in recent years and the team has kept on rolling In terms of the team's overall record with Matthews out of the lineup, the team has actually performed really well.
As shown above, out of the 47 games Matthews has missed during his NHL career, the Leafs have only lost 17, with two going to OT, leading to an single point for each outing. Knowing this, it sure isn't as alarming when you no longer have a player of Matthews' caliber in the lineup. Now, after having won last night's game against the Preds, the Leafs are now up to 31-15-2 with Matthews on the sidelines.
The Leafs are pretty solidified in the second/third spot of the Atlantic Division, and given the team's stats, even without Matthews, I don't think that will change drastically while he takes time to mend.