As a Sens fan, I'm guessing that if Hasek retires, and Ray Emery becomes their top netminder, that he'll be rookie of the year. He's a very solid and hardworking player, has played 3 seasons in the AHL quite well, and I hope will turn in a Raycroft like year. Playing for the Sens, he'd also be given a great opportunity, as there are few odd man rushes and that sort of thing.
Barring that, I expect that Kari Lehtonen will easily take the reigns of Atlanta, and become one of the league's top netminders. Atlanta has needed a goalie that could post more than a .900 save percentage for some time, and look for Lehtonen to have a .920 to .930 IMO. He plays well beyond his years, and will hopefully make Atlanta not only a playoff team, but a contending team.