Converting back from Device&User mode

I understand you (as in FreePBX team) don’t want to expose the d&u plumbing any more, i’ve no problem with that;

So I searched some community posts, including

and articles

(btw all pictures are gone here…)
and with the D&U mode on its way out in FreePBX 13, I wish to ask a question opposite to Switching (Converting) from "extentions" to "deviceanduser" mode :
What happens to ‘devices’ and what to ‘users’ settings when changed mode back to ‘extensions’ ? What happens to their (users, mostly) call recordings and CDR records?

Will the settings be transparently converted, to its own ‘extension’ number each, so the endpoints still can log on using their SIP credentials and secrets?