Wal-Mart, Sears, Costco, target, dollar general, Sam's Club, etc could do the same thing. FedEx, ups, and USPS aren't beholden to Amazon. Likewise, how hard would it be for grub hub and the like to detail their drivers to make last mile deliveries from local stores? I'm serious. Is it 1000 work hours or 10,000,000? Hell if I get laid off I'll need work and slinging boxes out of my suv is as easy as it gets while providing a valuable service in a crisis.
Let's be real here, Amazon, the online shop, is not "absolutely critical". If they closed today for 15 days, a lot of people will not even notice. Unless you are a shopping, in which case, well that would be a great time for a desintox and expand your world view :-)