Florida
Toronto
Boston
Tampa
Detroit
Buffalo/Ottawa (honestly a coin toss)
Montreal
Florida can fall off hard if Zito doesn't come clutch this off season. On the back end, Montour, OEL, and Kulikov need new deals. A lot of their playoff depth (Lundell, Cousins, Lomberg, Okposo, Stenlund, Tarasenko) and 50 goal Reinhart need new deals. They have capspace to sign a lot of players, and are an attractive FA destination, but the team will be very different from what we see today imo.
Toronto is a regular season team. Matthews will get his 50+ goals, and they'll choke.
Boston has the same issue as Florida, they have loads of depth they need to re-sign, and losing Ullmark will probably cost them a win or two.
Tampa is declining, but guys like Kucherov can still drag them into the playoffs, and that's without Hedman, Point, Stamkos, Hagel, Sergachev, etc.. playing their best.
Detroit just lacks star power, but they have all the pieces and depth to compete for a WC spot.
If Buffalo can get a 1A goalie, they'll be fine.
Man I hope we can get out of the bottom of the Atlantic