The answer to your basic question is simple . In the case where NFL says the game goes on, the Bills would have to forfeit the game and take a loss while New England gets a win.
On the other hand , if NFL is regularly in contact with teams and listens to preferences about needing more time to cope, they may very well postpone the game .
However , one must remember there are huge logistics/ financial impacts from a postponement . And NFL players are employees just like everyone else. Workplaces don’t stop work for weeks because an employee had a cardiac arrest on the premises .