I find this to be an interesting subject. Would you say Nashville had an affiliation with an NFL team prior to getting one of their own?
I live in Charlotte - which is also an entrenched city towards college sports. However the NFL was poplular too with many Redskin fans and some Falcons fans, mostly, IMO. So the transition to a home NFL team was easy for the natives. Then they had some transplants change from their home/born team to the Panthers and a bit of casual fans that participated. It took some time to get the numbers needed but I'd say at this point Charlotte, surrounding cities and even cities hours away have made it a decently strong following.
It won't work everywhere so I'm curious what you're seeing there?