I still believe that they will either send Montembault to Laval and grab a goalie off waivers to back-up Allen, or acquire an experienced goalie for Laval who has cleared waivers. They will probably have to do that to avoid Primeau being an injury call-up. Poulin is not even under contract with the team, and neither are the other two.
The othes are under contract. They don't have to be on an NHL deal to be part of the organization and have spots in Laval and 3R.
Also, I don't see them claim a goalie off waivers just to pick them up. If the timing syncs up at having an injury and then a goalie goes on waivers, then I see them do it (similar to how Monty went on waivers when Habs knew Price was not returning).
But if the timing doesn't sync up, then they can't claim a goalie off waivers if there isn't one there. If someone gets hurt, then they'll look at the market similarly to how they got Andrew Hammond last year.