That section mainly covers British expats still in HK after the handover. They lose their Resident British Citizen status, but are still granted ongoing permission to remain provided they do not move out for a period for 12 months or more. I reckon a lot of them will either have become permanent residents under the 7 year rule or have permanently relocated back to the UK.

Doesn't really cover BBCs and grandfathered BDTCs ROAs.