Cathar
If the Isle of Man were to adopt FAA standards, aircraft on an Isle of Man register could not be based in the UK under the DfT proposal.
I don't think anyone suggests they adopt FAA standards, where aircraft (which is the main DfT thrust at the moment) are concerned.
A hypothesis for you:
IOM registry adopts EASA standards, thereby allowing aircraft to be kept in the UK.
IOM issues licence validations based on ICAO licenses - which would include FAA certificates and ratings. (the main reason people go 'N' reg - IR privileges)
DfT is happy
Owners happy
Life continues as before.