Microservices are never deleted. They are only abandoned and left to rot after the initial developers move on to their second system (https://en.wikipedia.org/wiki/Second-system_effect). Then you have apps that are stuck in migration purgatory, where they haven't fully switched over to the new microservice because the business doesn't want to spend that effort, but they do want developers to focus on using the new microservice and new API for new app work. The hope is that app will eventually be 100% on the new microservice, but after 3 years you start to realize that is never happening and by that time the company has an entirely new staff working on a much newer microservice that promises to fix all the problems with the prior microservice.

That microservice kool-aid is strong and deadly.

> replace it with something that conforms to the same interface

ha. hahaha. Oh my. I'm in the process of switching over a REST service to a GraphQL service. Because apparently people wanted all the pain of SOAP, but "could I get that in a JSON flavor, please?" Five years from now, REST will be making a comeback under a different name. You heard it here first.