We had a pizza place like that. The original owners had made it successful by hard work, and they decided to retire. Some dilettante bought it and ran it into the ground in less than a year.
Down the street from my office was (once) a truly exceptional sandwich shop, not part of a chain, owned and operated by Lebanese couple. After many years, they sold it to a much younger fellow, who had worked for them for a couple of years, presumably learning the business.
I wish this was a happy story of a successful transition.
Truly.
But it is not.
As soon as he took over, quality went downhill starting with significantly inferior bread. The rest followed. He managed to hang on for about 18 months before going out of business.
The restaurant business can be tough. Something simple like changing the ingredients of the pizza and you will lose long time customers.