Please set your sights a bit higher than this. A Marner trade has to fully address this team's depth or add a significantly impact defenceman.
Being cost controlled or physical should not be the main selling points of any player the leafs get back. Impactful and potential are the words we need to focus on.
There's a tipping point for the organization in terms of minimum acceptable trade return which we don't know, and another spectrum of value for individual fans which the club doesn't care about but which determines how happy we are with a deal.
At one end of the scale is cap space alone with an own rental Mitch which would be a complete fail. There will not be the same plethora of quality RFA defensemen as this year so how just money can improve the team is much more uncertain. You are running it back with just the new coach as a significant change so there is a strong likely hood of the typical result. Basically a lost year as you are banking on Tavares departure and further cap growth to allow the lineup to improve. I assume they would make an effort to resign him but it would be for market value rather than Leaf numbers.
At the other end is the return of high quality assets and significant value which you could have pursued without the NM and get the most back from the thirstiest dance partner. I think they sort of went down that road with Willie but were not getting sufficient value so they didn't deal..
Any Mitch deal is somewhere between those two points. If he will even agree to waive there will likely be a very limited number of options so the return will be underwhelming. Like the Flames for Hanifin because he had the NM and pull on the destination so rather than the best return it was the best available return from just a few teams. As such any Marner deal almost certainly can't fully address the teams needs any more than a Nylander trade would have. If that is what you would need then you will really need is for him to be resigned. If the organization needs that same return, he will have to be resigned. I for one expect they will be flexible if a deal can be made as the news conference did not suggest an appetite to run it back again. I don't know what their tipping point is though in terms of minimum..
They will be able to add a significant defenseman with the cap space alone irrespective of the trade return because there are 6 RD out there who are better than what they have. They will likely have to take the best offer, whatever it is, and use those pieces towards more specific needs. They aren't calling the shots, the player is, so it is really important he isn't too specific with his destination, or at least he keeps it quieter than Hanifin's people did because Vegas knowing the other two prime destinations crushed the Flames return.