The Bills have said they are probably not going to be francising Brown; they may want to reconsider that if the Dolphins show serious interest in Brown for it would be a double hit to be facing Brown every year.
According to NFLTalk:
The Dolphins are said to be very interested in pursuing Bills guard Rueben Brown in free agency. Not only would Brown give Miami a dominating run-blocking interior lineman that they’ve been lacking for years, but it would also weaken a division rival. Brown, who is an unrestricted free agent, should command a contract anywhere between $4 and $5 million. The Bills said late last week that will probably not be franchising the Pro-Bowler.