I'm all for it but it's hard to do capwise. If MB can pull it off, sure. That means definitely let go Tatar and another winger or two. Seattle expansion might help there. But I definitely prefer C depth to wing depth. You can get cheap depth wingers everywhere. Besides, who cares about the fourth lines when your first three have Dubois, Suzuki and Danault.
This is the key, especially with a head coach like Julien and quite a few others around the league. If your C-line is a strong, two-way line that can play indiscriminately against any of your opponents, that type of coach will roll out the line pretty evenly and the fourth line's TOI, depending on the quality of that line, can see it's TOI cut back. Rolling out three lines that you can count on to stifle the opponent's offence and score goals for your team at the same time is not like needing to rely on one or two lines that you overplay like the oilers or Leafs might.
Having a fourth line that can play D for shorter shifts (going balls to the wall) is relatively easy to assemble at near league minimum. Plenty of players who fit that bill are up for grabs, even on the waiver wire.
Quality depth over your top-9 is the key.
Montreal should be able to align a roster with the following top-9 for the medium term, no problem, even with extensions to Tatar (4), Danault (6), Dubois (5), Suzuki (6), Romanov (bridge for 2 or 3), Drouin (6), etc...:
C: Dubois, Suzuki, Danault
LW: Tatar, Drouin, Caufield or Toffoli
RW: Gallagher, Anderson, Toffoli or Caufield
Players like Byron, Armia and Lehkonen are, unfortunately, necessary casualties over the next two years if all the above the top-9 are to be re-signed. We can't have 4th line depth players at 2.6M (or more) in Armia and 2.4M (or more) in Lehkonen -- definitely not at 3.4M in Byron! Ylonen, Poehling, Teasedale, Mysak or, cheap depth veterans on short term contracts are the options we will focus on.
The D is another matter but, its also pretty sharp over the next four years. Yet, more movement will be needed on the backend with ELCs stepping in to help the cap situation. Ideally, Bergevin can move his forwards without relying on Seattle to take one on. Based on Romanov's projected progression this season, that could set the habs' GM up to make an offer for the Kracken to take on the three remaining years of the Edmundson contract and free up the 3.5M. Montreal has cheap alternatives for the 3rd pairing out of Mete, Fleury, Brook or an ELC to one of Norlinder, Harris or Struble (Guhle should get a bit of time, IMO).
With the help of the Kracken, Bergevin would get an easy out of Chiarot's 3.5M Cap hit at the end of the following season, whether he were to decide to move him at the deadline as a decent rental or to ride the playoffs and risk losing him for nothing in the offseason. Either way, the cap space is more valuable than extending Chiarot would be. This would require another ELC and, perhaps, Guhle would be the appropriate target to ease his way into the NHL on a 3rd pairing as a defensive anchor alongside Brook?
Romanov - Petry
Chiarot - Weber
??? - ???
Mete, Fleury, Brook, Norlinder, Harris, Struble as options or a stop-gap veteran signing on the UFA front.
Primeau would get one more year in the AHL next season but, would also need to step up as Allen and his 2.875M Cap hit couldn't be around when we need to extend both Dubois and Suzuki at the same time.