What happens to those well-maintained chargers when more/all cars start using the Tesla standard for charging?

Tesla makes money and has made most EVs out there. I doubt the remaining customer base is large enough for the other companies to make a profit.

In only 11 years Tesla built the world's best EV charging network to cover the entire US interstate system, highways, major cities, important destinations, and more recently even medium and small cities.

I'm confident Tesla can expand their network to cope with additional demand and in a relatively short amount of time. Expanding an existing site is usually a lot faster and cheaper as well.