Good topic and I can honestly answer that one because it happened to me. Here's my story (if anyone is interested, sorry if it's a little long).
I'm from QC city and grew up as a Nords fan. When I was little, I "had" to pick between the Nords (who joined the NHL when I was 3) and the Habs (older people like my dad were long time Habs fans and didn't make the switch). Of course at 6 or 7 years old I was too young to make a rational decision and I picked the Nords because, as a little boy, I liked the blue jerseys better. From then on I became a Nords fan and regardless of what happened, I'd live and die with the team. We went through some tough, tough years together but we were looking ahead and had a bright future.
When they moved to Denver, I kept following the team (many of us did) because we knew all the players and they were "our" kids. We suffered for many years to get that team and were emotionally attached to it. In 1996 when they won the cup, I felt pretty much the same as if the Nords would have won. I bought an AVS hat, followed every game on TV, watched the SC parade and so on.
But then the years went by, and players were slowly replaced until the point where it wasn't "my" team anymore. I remember watching the SCF in 2001 and while I was rooting for the AVS, it didn't feel like it was "my" team like in 1996. It was awesome to see Forsberg and Sakic but it would have been almost as awesome to watch them in any other team.
So after a while I moved on and just stopped watching hockey altogether.
That's until last year when Roy came back, I was curious so I started watching and quickly became an AVS fan again. I learned a lot about the current players and such by reading this board and watching the streams on the internet.
Right now I'm just happy to be a hockey fan again. If/when we get the Nords back, I'll be a Nordiques fan but will still have a soft spot for the AVS.