She had a good live.
Not every Slayer could say the same.
Buffy had luck, by the time the Empire took over she had an British citizenship.
Xander was in Germany at this time protected by the EU.
Kennedy was in Japan having lived there with her Girlfriend.
She was one of many that didn't make it. The moment the Empire took over she shot herself.
Buffy didn't need to ask why.
One who once lived his life in freedom could only brake down in slavery.
In Area 11 Rebels under the command of an eleven calling himself Zero have committed another attack on the Empire.
Maybe it was not to late to hope.