I understood it the same as you:
Ionic Auth login stuff (register form, password reset, OAuth integration) will go away and it will be like a “database” of users that you can set in your app, probably receive a “user_id” back that you then can save on your server and connect to your own user database, so you can then do “I want to send this user a Push” and can connect your data to Auth data which then connects to the push token.
So starting with something using Ionic Auth might not be the best idea…
But of course this is just my interpretation. No idea if this is correct.