I think that Berube's seat might be a bit warmer than most guys who are less than 2 completed seasons removed from a Cup win. But I don't think there is much chance that he is gone before next season. We were the 2nd best team in the regular season last year, so it isn't like we've struggled since the moment we won the Cup. We can debate correlation vs causation, but all the failure to meet expectations have occurred within the weirdness of COVID protocols (playoff bubble, round robin return to play, division-only schedule, 7 game series vs the Yotes, etc). There has also been a healthy dose of injuries along with the team being hit with COVID before playoffs last year. Again, we can debate about whether these are excuses, whether he should have had the team better prepared, etc. But I think it would be foolish to fire a coach who has demonstrated clear success in times of "normalcy" based only on his failures in times of non-normalcy.
If we get smoked in round 1, I won't be surprised if Berube is on a pretty short leash next year. But I'd be very surprised if he isn't given the chance to show that he can get the team back to winning with a normal camp, starting at roughly the normal time and playing a largely normal 82 game season.