When did amazon become UPS's only business? Will losing amazon hurt UPS? Yes. Will Ups go under? No. Plenty of other business out there to keep us afloat.
Ain't going to happen. Amazon will move volume around between carriers. But they wouldn't take it all from one. Nobody could take all the excess volume. Not even the postal service.
Years ago here in upstate New York we had Kodak film big shipper with us. When ever they went on strike we would have lay offs. Now they are almost ( if not out of business) some how ups is still here with out them