IIUC, the analysis assumes other systems would also be disrupted, as modern devices support multiple location services (gps, galileo, glonass). So there isn't

IIUC, the analysis assumes other systems would also be disrupted, as modern devices support multiple location services (gps, galileo, glonass). So there isn't really a case of GPS failing while Galileo works and viceversa, it's just "everything fails" vs "something works".