It would “end” fast.
Most hospitals have a week’s worth of limited generator power. Phone and internet would fail. Deliveries would cease.
It would take “just a little” longer to recover from that.
In my prior life as a telco engineer, the battery strings providing -48 VDC at a steady draw of 20,000 amps in the central office were standard arrangements. The AC mains drive rectifier bays to charge the batteries. Outside, an emergency generator running on diesel (30 days fuel onsite) or natural gas (co-gen plant could switch between gas turbines on natural gas or diesel generator backup). The landline phones were powered from the central office. Much of that model is deprecated in favor of wireless technologies today. Many more customers power their own CPE (customer premises equipment) from AC mains. Few have the foresight to have a UPS for phones/routers.
My local city has diesel backup good for a week for city government. The 5 city water pumps are electric. The pump sites appear to have an onsite diesel backup. Ditto for the water pressure boost pumps.
Loss of grid would be a game changer. Hard to get fuel. Refrigeration down in businesses with rapid spoilage of food in the stores. That happened in San Diego with the rolling blackouts. Hospitals have some backup, but no location has infinite ability to run.