We're preparing to launch Apigee X, the new generation of Apigee SaaS, very soon.
There are a few changes with Apigee X - and the dependence on Google identity is one of the foundational changes.
This means, when you adopt Apigee X, you will authenticate to the administrative APIs in the Google fashion - only with OAuth2. Basic Auth is not supported.
If you're building a CI/CD pipeline or other automated tools to interact with the Apigee Admin API, then you will probably want to use a service account to authenticate.
I've put together a screencast showing you a couple ways you can do that , either using the gcloud tool, or using a hand-rolled script and curl commands.