They don't 100% have to, but unless the rumours of something around $12+M per year are true, I think it is likely their intention.Seriously.
Trading Nylander in order give Marner a terrible contract would be the stupidest thing a Leafs GM could do....
Nylander + 4 1sts + 11+ mil in capspace >>>>>>>>>>>>>>>>>>>>>>>> paying Marner that insane contract.
Some folks really have to get past the idea that the Leafs 100% have to sign him no matter how much he asks for and how damaging it will be to the team and its competitiveness.
We cleared cap (while, in my opinion at least, improving) without trading Nylander and Marner already, and we can do it again.