Yeah that's not happening.
The concern goes like this...
Take for example, the Aho contract that Montreal offered... the compensation was only 1-2-3 picks. If that was offered in late November, the Leafs could not afford to match because of this year's cap hit.
Here's the thing...
1) The Leafs could still make a trade to free up the space to match.
2) Why would Marner sign such a contract. I seriously doubt that the Leafs haven't already offered more.
The sticky situation happens if some team offers something like 10.5 * 5 in November. That becomes quite difficult to match and the compensation is 1-1-2-3. I have to think an offer in that neighbourhood has already been made by the Leafs, or close it. If the Leafs are even close, I doubt Marner wants to leave Toronto for a small difference.
Finally, a team has to have the money, and the cap space, and they better know they can sign all their own RFA's in the next couple years
It is difficult to see a scenario where Marner leaves via an offersheet.