The first related article implies pretty strongly that they will delete most of your data from their storage, and even backup storage. It may take up to 90 day

The first related article implies pretty strongly that they will delete most of your data from their storage, and even backup storage. It may take up to 90 days to delete data stored in backup systems. Your info isn't accessible on Facebook during this time. Copies of some material (example: log records) may remain in our database but are disassociated from personal identifiers.