If all the games are selling out, then it doesn't matter what kind of "pathetic shape" the city of Buffalo is in financially. As long as the tickets sell, the Bills will be in Buffalo.
A new stadium could be a very good thing for Buffalo, if they do two things. 1) Make it have a retractable roof and 2) Put it on the lake and use some of that old Bethlehem Steel and NFTA brownfield property. A lot of people in OP would feel the pinch from the Bills stadium moving towards the city, which would suck, but it's the Buffalo Bills not the Buffalo Bills of Orchard Park. If the politicians up there could get their heads out of the sand and come up with a plan to fund a new stadium, it would work out really nice. Not only would the Bills get a new stadium, but it would give downtown the convention center that we've been hearing they need for as long as I could remember and could possibly put Buffalo on the list to host the Super Bowl. Not to mention put some of that waterfront to use. Personally if the city ever did host the Super Bowl and media slammed us like they did Jacksonville, that'd be fine by me just as long as they're spending the $$$$ while they're doing it.