Thanks Ben for the announcement.
The MariaDB modules are available for testing right now in Rawhide and
in BODHI. 
I'll be thankful for any testing of the modules, so I can look into
any issues that might appear, before getting the MariaDB 10.5 in the
Fedora Rawhide base.
MariaDB upstream aligned their release cycles to be more predictable.
A new series should come out every year.
With that said, I look forward to similar Self Contained Changes with
similar failover mechanisms (modules of the current and new version
available), so I'll also be glad for any tips for improvements of
handling this and similar changes.
Core Services - Databases Team