I suspect they will eventually migrate time machine backups in one go to APFS+snapshots, then use the new ASR tool also mentioned in this talk to stream local t

I suspect they will eventually migrate time machine backups in one go to APFS+snapshots, then use the new ASR tool also mentioned in this talk to stream local time machine snapshots to the volume. I also suspect that will launch 'soon' (after September but possibly in March) , but I have to imagine the complexity and testing requirements for such a in-place migration are staggering.