However since I initially saw the news of these drives a few days ago Samsung also axed some Linux devs, which gives me pause and makes me reconsider the long term viability of this filesystem...
I believe Ceph now has abstracted the drives away through BlueStore, which simply puts a large RocksDB database on the drive, bypassing most of the functionality a filesystem offers. It should be much easier to make an SMR compatible version of the LSM-tree backend of RocksDB, than writing a full-blown file system.
RocksDB is one of several possible backends for object maps. There is a lot more to BlueStore than just omaps.
Also, BlueStore was actually designed with SMR drives in mind, however certain components of it are best placed on solid state media.