Combining Galera and asynchronous replication in the same MariaDB setup, aka Hybrid Replication, can be useful - e.g. as a live backup node in a remote datacenter or reporting/analytics server. We already blogged about this...

Hybrid replication, i.e. combining Galera and asynchronous MySQL replication in the same setup, became much easier since GTID got introduced in MySQL 5.6. Although it was fairly straightforward to replicate from a standalone MySQL server...