I'm betting Tavares is not coming off the books at all. He'll re-sign for something like $4-5M less, at least some of which will go to Marner's raise.
That'll leave the Leafs with at best $3-4M in freed up cap space and that doesn't include any extensions & raises for existing players like Knies, Woll, Domi? Also, Brodie won't likely be back which frees up cap space but also means his spot on the top pairing has to be filled, and probably for not any less than his current $5M (Lilegren is not that option, at least not yet)
So everyone please get past this notion that once Tavares is gone (and he may not be at all) and the ceiling is raised it's going to be raining cap space in Toronto and all the teams' worries will be taken care of. It's not, not even close.