While Schneider is a solid defenceman, the drop-off in mobility between him and Matheson would be stark. Without Matheson, our team would be much more vulnerable to a strong forecheck and less dynamic in transition and in game situations where speed and fluidity is paramount (4 on 4, overtime and the powerplay). Unless you are able to replace Matheson's mobility, any transaction where Matheson is traded away would constitute a material step backwards.
The reality is that it would be near impossible to replace Matheson's skill levels with any player who has a sub $5 million contract. What people forget is that in the construction of any NHL team, cap implications are as important a factor as projected on ice contributions. For that reason alone, it is highly unlikely that Hughes will be moving this extremely cost effective player.
Cost effective for just another year after this, all while Matheson's low Cap hit is more valuable to another team than it actually is to Montreal, a team that isn't in a cap crunch and whose ability to eat up to half of Matheson's already low Cap hit for this year and next can further increase the veteran D's value in a trade.
Your analysis of his mobility is a little harsh, IMO. While he might not have the exact same fluidity as Matheson on skates, Schneider's skating ability is considered one of his strengths, along with his defensive chops, the physicality in his game and his ability to play big minutes.
If Schneider were to play alongside Hutson, for example, Hutson could be the elusive skater that carries the puck up ice on that pairing.
After that, either we continue to pair Carrier with Guhle, with similar results to when Carrier was playing alongside Ekholm, or Reinbacher eventually earns a shutdown role alongside Guhle.
Xhekaj - Carrier
-OR-
Xhekaj - Reinbacher
to round things out.
With Mailloux playing in a beer league somewhere, based on your analysis of how horrible a D he is and how close he is to being proclaimed a complete bust.