I think if you wanted Helle and Ehlers the ask would not be Marner but more what you are giving Calgary for Kadri and Hanafin.

Accepted

Matthews either wants to play in AZ, or he doesn't. It's A or B. Either he wants to play for the hometown team despite the on-going situation there, or he doesn't.
If he does, they can wait one season and sign him without dealing assets. If he doesn't, why would they ever stunt their rebuild with a deal like that for a year of Matthews? No reason to trade for him from Arizona's point of view. It's not like they'll want him for next year's playoff run.

two first for a season on Nylander? Probably a pass from the penguins. I'm not putting two firsts in a trade unless it's Marner or Matthews personally.

Not to mention i've seen leafs fans on here sending him away for less.