Even with a lot of issues last season, they finished with over 100 points.
As mentioned, only losing Bertuzzi and Samsonov isn't going to make or break the Leafs. They both had pretty terrible seasons with some good stretches. Leafs have made plenty of solid additions that should give them a good rounded team, along with some younger options hopefully taking a step up in production.
With that said, you just never know. Sometimes a team just falls flat and goes through big injuries. Look at NJD this past season. It would be a very Leafs thing to go through a rough patch without a 1st round pick.