Indeed, the chances that he will be sidelined for several months, possibly even 6 months or more, are quite high. In the best-case scenario, he would return six weeks after his surgery, if it's the meniscus that is affected.
According to insider Frank Seravalli, there is a glimmer of hope, as surgery might be ruled out.
I don't know what the diagnosis would be if he avoids surgery, nor how long he might be out, but it's certain that it would be shorter than 6 months.
Currently, many things are being said. 4 to 6 months and season-ending are the updates that come up most frequently, but we will really have to wait for the official verdict from the Canadiens.
Chantal Machabée had hinted that it should arrive Tuesday morning, but that hasn't happened. This means that Frank Seravalli is probably right and that surgery might possibly be avoided.
This is a file to keep a close eye on. Personally, I expect an announcement any minute now. We had the one about David Reinbacher, who will be out for 5 to 6 months, and we will soon have the one about Patrik Laine.