Ive been a Mavs fan for 8 years and Dirk's been a constant during these 8 years. If Dirk was traded in the 2nd year I would've still remained a Mavs fan and perhaps wouldn't have had as great an appreciation for Dirk as I do, now if Dirk was traded or retired I would still be a Mavs fan but I can't say there wouldn't be an emotional withdrawal from the franchise. I feel like this is just natural. If Dirk was traded to another team I would definitely have a rooting interest in that team as well. I wanna see the Mavs win a championship but would feel great joy to watch Dirk win a title as well, even if in a different uniform.
I don't think this makes me a bad or bandwagon fan, I really do (somewhat irrationally) feel pain when the Mavs lose and joy when the Mavs win. I really do root for them and try to watch every minute I can. Isn't that what being a fan is?