The door is opened: all RADOS gateways in the cluster are using the same object space. No federation or multisite headache required: just create the additional gateways at the nodes, synchronize the CEPH configuration and list the gateways names/IPs in the client / load balanser / HA proxy daemon.
https://www.mail-archive.com/ceph-users@lists.ceph.com/msg25994.html
The most reasonable and ‘musthave’ feature appeared almost not documented.