I think multi-tenant capability would be a really great asset for gluu server.
Let's consider this scenario: ACME business provides a SAAS, where each client is another company:
Each company would want to individually theme its login page and fine tune its tokens properties (like expiration time, whether it's opaque or not and so on). A user (identified by an e-mail address) could have accounts on both companies with different passwords and MFA setup.
From what I understand, the only solution to accomplish this is to deploy gluu separately for each tenant, which quickly becomes unmanageable given thousands of company clients (those servers need to be deployed, replicated, DR).