As a young kid in Quebec, I despised the Habs because it seemed like everyone liked them... just because of their history. When I really got into hockey (I watched Nordiques games with my father) I started cheering for Anaheim because I loved Paul Kariya and wore his number. I remained a fan of the team until he left and followed him to the Avs, but I did not really care for the Avs, so I drifted away...
Until 2004-2005, when I finally got into the Habs as some of their players were fun to watch. Eventually, I really got into them and I have been a fan since then.
So, yea, I am proof that it is possible to change allegiance over your life.
Also, I think that it is harder to switch teams when you love hockey only because of one team. I love hockey for the sport itself and I enjoy watching other teams. Therefore, my love for the sport remains even if a situation brings me to abandon a team.
P.S.: I still checked on Anaheim for a bit, but they did everything to change the team. The name, the look, the image, and the players.