Xfinity mobile as a back up

Xfinity should be installing mobile SIM cards in all their WiFi routers so that when their system goes down, the landline at home switches to the mobile connection and still can make calls (and maybe limited internet). Power was off in CA the past few days and now that it is back, Comcast is still down so no landline for emergencies.
A home generator will keep the power on in the house during outage but doesn’t help if Comcast can’t keep their network running without generators (which they should have).
Comcast/Xfinity, your thoughts?