Beck should be in the mix next year. Mailloux might be if he can play D better than he has so far in the AHL this year. The habs don't have to decide if Dach is a C or a top 6 next year, but they need to know before they can compete. If Dach continues to make really bad giveaways in bad positions they will have to get him off the ice once they park the tank.
If there is an opportunity to get a top D or a top C due to the incompetence of some other team the habs will have to jump. It's uncommon, but it happens.
In two years or so the habs will need to get some solid vets, not necessarily first liners, but player/coach types, plus a solid shutdown forward or two.
They'll need at least one and ideally two top Ds, you have to hope one of those guys will be Reinbacher, but if he ends up second pairing or worse they need to go looking.
In a perfect habs world one or more players would grab the open spots, including, possibly, a high pick in the next draft.
It's not like they will be short a bunch of players. Dvorak won't make much difference. Armia can be effective, and they would need to replace his size, but it's unlikely to be a major problem. Assuming Savard leaves it will be a problem for RD depth, but it's not like his play this year can't be replaced by pretty much anyone in the pipeline. The issues are going to be top guys and team composition, notably defensive players (F and D), and making up some size with Hutson, Gallagher, and Caufield out there.