Central authentication service that authenticates on user login and passes back and API token to be used to access other services. With something like a JWT you don't need to check the User database for every API call.
Yes, implementing all these features as microservice won't simplify the architecture, but you'll at least be able to easily migrate upgrade, remove, replace or scale up pieces of it.
IMHO, you're painting a very rosy picture here. There is a big assumption that you will want to preserve existing interfaces (REST APIs?) between those microservices. In reality, they probably will be bloated and obsolete just like everything else you have.
And being forced to update "microservice" at a time rather than as a whole, the whole process will actually become more complicated.