...will it immediately become the default authentication method for end users or will the previous authentication method, which is a token based authenticator authentication, stay active until I turn it off.
Hello,
When enabling Microsoft Authentication (Azure AD) in DVLS, the other authentication methods are still available unless you disable them.
Finally, if you want the existing users to use Microsoft Authentication to connect, ensure to migrate their accounts and the user groups properly using the Authentication Migration Tool.
Let us know if you have further questions.
Best regards,
Érica Poirier