Six full time developers who wrote 15 microservices that each do one thing well should not be fired. The burden of microservices lies in the underlying infrastructure required to host them. So, assuming we have a competent infrastructure engineer, devops engineer, security engineer, site-reliability engineer, and a handful of other hats being done well... your six developers can write and maintain far more than 15 microservices assuming that each service has a clearly defined single-objective scope.
Because infrastructure complexity <> Software development complexity.
Because infrastructure complexity <> Software development complexity.