I really do think a lot of football fans would be bummed out if the Bills left. Not to the point of boycott or anything... But Buffalo is a decent piece of the heritage of the NFL. I have lived a few places outside of WNY and not a lot of people hate the Bills or the fans. A ton of people have crazy stories of attending a game at the Ralph and/or living with/working with a huge quirky Bills fan.
Someone said it above, but Bills home gamedays are some of the only really authentic NFL experiences left. From the tailgate, to the crowd noise, to the ordinary Joes in all classes of seating.
after the Monday night game against Cleveland, someone on ESPN page 2 wrote up a really complimentary article about the Bills fans/atmosphere. The same article tore apart the Pats' game day experience.
I believe we are viewed around the league's fans a lot more toward the Green Bay Packers than the Los Angeles Rams.