Since the Leafs would potentially be in a bind if I were MB I'd call Dubas and say sure I'd take Marleau off your hands, spend to buy him out and take his full cap hit so you can maybe re-sign him. I know you won't like the cost Kyle and I highly doubt you'll accept it but I'd do it for your 2019/2020 first and your 2020/2021 2nd for a 2019/2020 5th and someone like McCarron to make it look more legit.
Dubas would rightly refuse that steep offer but if I were MB I'd tell Dubas I'll leave the offer on the table until the last minute just in case he can't find another team to possibly bail him out if he really needed the cap space. It's business and if you have a chance to take advantage of another team to better your own team why not try it right?