I was still living in Oakland when Al Davis moved the team to L.A. I was not a Raider fan, however 99% of my friends and family were. They all TRIED to remain fans of the team and simply couldn't, it made them sick to their stomach to see the team on TV. Yes, there were exceptions to the rule (of course). The people I knew stuck it out for a while and turned their attention to other teams or, as Dave suggested, lost interest in the league altogether for a while.
I was just a couple hours north of you when this happened and I was a huge Raiders fan, but when they moved I gave up on them. I felt betrayed by Al and his ego.
If Miami moved I would probably switch to Seattle( they are in my neighborhood) or spend some time afloat searching for a new team.