Next major release version 4.0 will be stable support for multiple external user directories. At the minimum, the following new user directories will be included (in alphabetical order):
Apple ID
Facebook
Google
Microsoft Account (consumer-grade)
Microsoft Azure AD
MPASSid (OpenID Connect based variant)
Trivore ID (Trivore Identity Service)
Generic OIDC (OpenID Connect)
Generic SAML (Security Assertion Markup Language)
The generic user directories add the capability to add corporate private and custom user directories.
For completeness sake, already existing user directories are listed here:
Generic LDAP (Lightweight Directory Access Protocol)
Microsoft AD DS
Microsoft AD FS
suomi.fi SAML
simple REST API for cross-platform account migration
Target for this release is 1Q 2021.