I'd expect Hyman/Matthews/Marner to play together more frequently next season.
Not sure I agree as both Matthews and Marner drive line offense and together the sacrifice is felt on the other lines.
The cause and effect of this move might see the Leafs become top heavy and more a one line offense like Boston with all the other lines more support lines.
A Marleau -- Kadri -- Marner line when firing on all cylinders takes both some the offensive load and weight off the Matthews line, as well as draws some of the opposition top defenders away from Auston as well, allowing 2 lines to split/share advantages, home and away.
With JVR and Bozak both likely leaving that means Leafs depth will be tested.
Spliting Mitch and Auston isn't about punishing either player is about balancing offense across more lines.