If the Canadiens lose Cayden Primeau via waivers in the latter stages of training camp and DeSmith is still around, there's a possibility they could go with three goaltenders on their NHL roster, like the Calgary Flames are potentially going to do. But eventually, they'll need to stick with two of them and roll with it.
Samuel Montembeault isn't going anywhere anytime soon, but as the season drags on and teams are looking to add a backup goaltender with experience for a potential playoff run, Jake Allen and Casey DeSmith could become options. We know full well that injuries are unpredictable and can happen at any time, so if there's a team who is struggling in goal due to injuries, it could very well open the door for DeSmith, helping him to find a new home where he'll actually have the chance to play this season.