missing the playoffs 7-8 years in a row would probably make me stop watching
We went 9-10 in Carolina. Frankly, I went to many more games during that stretch than I have in the last 6 years. Mainly because I was a STH for much of it until my kids grew up and moved out. Even after I gave up the season tickets, tickets were cheap so I could go to games cheaply.
For me, it would be moving/relocating. I grew up in MI and was a Wings fan for much of my youth. Not die-hard, but still a Wings fan. Yzerman was, and still is probably my favorite player of all time. Datsyuk is a close 2nd. I moved to the northeast US when I was in my early 20s, and over time, as some of the classic wings players I followed retired, I didn't follow them as much.
Then I moved to NC during the lockout and immediately got season tickets for the Canes in 2005, became a Canes fan and have followed ever since. Got to see the Wings/Canes play a great 3-2 game in 2005 and see Yzerman score a goal as part of it, but also watched my young kids become Canes fans at that game.
I suspect if I moved to say Nashville, or Dallas, etc...I would eventually migrate to one of those teams as a fan. Fairweather? Not really as I stuck with the Canes through 9 years of no playoffs. Just that I don't have that deep of an attachment to locations, more to players.