Not really. Not as long as they can keep the defense corps intact. If you have a strong D Core, along with a #1 goalie, you will be in every game. You don't even need a true #1, just a 1B may suffice if you are facing shots from the outside all night.
They have a few leaks. These leaks ironically also happen to take a great deal of the cap space they need. Clean the space, find some UFAs or make trades.
They need at least a very capable and reliable backup/maybe lots of starts goalie until Woll proves he can stay healthy for an extended period of time, something he has not been able to do dating back to at least his college days.
How has having half the cap tied up into two centers and two wingers worked out so far in the playoffs? And we're talking about at least the past 5 playoffs. Then look at how their scoring drops off dramatically in the last 2 or 3 games of a series. A change needs to be made here, and all signs are pointing to that being Marner.
McMann, it turns out, has an injury history similar to Woll. So can he be counted on in the top 9? Will the bottom 6 ever stay mostly the same from one season to the next? Hard to build any type of team chemistry that way.
I think, and it's only my opinion, that the Leafs need a legitimate top 2 rhd who the opposition must respect on the PP. How can that be done? Marner alone will not get you that, so what would need to be added? Or else the other team is sending you back a bad contract of their own. After that, you have Rielly, McCabe, and Benoit who are capable of playing in your top 4. If Benoit plays in your top 4, who are your bottom 6 dmen going to be? Maybe Edmundson, but I have a feeling he will have to take less to play here because I think there will be better offers out there for him. I can't see Timmins ever becoming a full time bottom 6 defender, especially when you consider his play in the dzone.
Again, it's just me, but I see this as a mess because you're not looking at fixing all of this in one offseason.