If Houston and LA can lose NFL teams, Buffalo can.
The number of people in the seats does not matter to the NFL, but the number of TV sets does matter.
Would more people watch the NFL in LA if LA had a team? I don't think it makes a difference. It makes a difference to the owners on profit from jersey sales and stadium profits. But TV revenue is a macro thing. The NFL is the top sport on TV. TV revenues drive the league. Owner egos drive things like the Dallas stadium.