The teams in the bottom don't have a real reason to fire their coach in terms of righting the ship. You can always do that in the summer and just play out the season. Sometimes they go with an interim coach, but yeah I never bank on those teams.
Sullivan, MSL, Cronin etc. are basically those guys. Maybe, maybe not.
The teams that are not in a good spot and still think they can be a playoff team already have coaches that were hired in the summer or last year, like Brunette or Bylsma.
I guess right now Montgomery is the only guy who fits the bill on an early-season firing, but the B's have won 3 out of 4 games so they seem to be getting better. And you can't have much more regular season success than what he had in his first 2 years, personally I think he deserves the chance to see through a different type of season.
I think the eyes will be on teams that potentially struggle later on and keep falling in the standings. Like LA last year, as well as a potential interim for the likes of Sullivan. But yeah I'm personally not expecting a firing right now.