Marner for Ekblad is the only straight up trade I can forsee. More likely he ends up somewhere like LA for futures.
For what it's worth, the Leafs really don't need to trade Marner
unless they're signing Pietrangelo; in which case they'll probably be looking for a $6-8m forward to offset his loss. They don't need or want to go from Marner-to-zero... they realistically need to find a way for their top 4 forwards to make about $2-3m less in order to accommodate Pietrangelo -- which is of course frusturating because $2m is just about how much Marner got overpaid by.
There are 16 defencemen in the league right now with contracts greater than $7m. They are:
Karlsson, Doughty, Josi, Subban, OEL, Trouba, Carlson, Burns, Chabot, Hedman, Weber, Spurgeon, Suter, Ekblad, Letand and Vlasic. The Leafs can comfortably acquire a $5m defenceman simply by moving Johnsson. They can probably figure out a way to stretch that to $7m without touching the big 4 up front.
Of that group, you've got 4 untouchables (Josi, Carlson, Chabot, Hedman), 7 guys that you really don't want (Subban, OEL, Burns, Weber, Suter, Letang, Vlasic), leaving 5 theoretical targets -- Karlsson, Doughty, Trouba, Spurgeon, Ekblad.
You're not going to trade a 23 year old Mitch Marner for a 30 year old Erik Karlsson or Drew Doughty. I don't think you're going to do it for a 5'9 30 year old defenceman in Jared Spurgeon. I don't believe Jacob Trouba would be willing to come to Toronto, nor do I think he has the remaining upside to be somebody that it makes sense to lose Marner for. I think Ekblad is really the only guy who moves the needle.
The guys who make less than $7m, either aren't good enough to "move the needle" for Mitch Marner, are too old, or simply too valuable to their teams because they're at the tail end of a really good contract.