I certainly would not be in a panic. Ever since the PO became an 'independent corporation' "to gain the efficiency of private businesses" it has done little but raise rates on First Class mail and decrease services. They want to eliminate Saturday delivery now as a cost cutting measure yet I have received no mail in my mailbox for months on Wednesday or Saturday, so as far as I can tell they have already de facto cut services.
Not to wallow in "the good old days", but I remember as a child the postman delivering twice a day to the homes in our neighborhood and the postal rate was 3 cents. During the holidays there might be as many as 6 deliveries per day to the house, each with a handful of Christmas Cards. We probably sent out 500-700 cards and received about the same in return. Many included a once a year bit of correspondence from old friends capsulating the news of the year of births, deaths, special events and plans for the coming year. People wrote letters! Of course as rates went up we wrote fewer letters, sent fewer cards and have embraced email, unlimited long distance and on line bill pay. The Post Office has lost almost all of my business. I have options so I don't need to pay their ever increasing prices for a stamp.
I know of no country in the world that does not have a government or quasi-governmental postal system. It is pretty much a requirement that there be an 'uncorruptable' messenger to deliver official notices. So I don't see the Post Office closing their doors--no matter how poor the service and expensive the price tag. And of course my answer to their fiscal problems is to raise the rates on the bulk mail that jams my mailbox and goes directly to the recycling bin. We have 'no call' lists for land line telephones, perhaps the same should be instituted for mail solicitations. And if bulk rate was higher we would probably not have received a dozen or more copies of the SAME Medicare Supplement brochure in the past week because senders would be a little more discriminating in how much of what they put out there.
As for the shops, I'm sure they will continue.