I believe they are signed through 2021 or something like that, but there's also a pretty inexpensive buyout option, something like $100k, IIRC.
A friend of mine is pretty high up the food chain at Fisher, and he told me last year the feelings there are that the Bills will be pulling training camp out. I think it's a massive bummer. The atmosphere there is just electric, and as a Rochestarian I love having camp here. The setup, by all accounts, is the envy of the league. And I love that I can be at camp in 10 minutes, vs. the 90 minute drive we make eight times a year for home games.