All EASA licenses issued by the UK CAA would no longer be valid and recognised anywhere world wide with the
That is not a given at this point. You are assuming that to be the case. If a licence was correctly and legally issued it does not have to stop having an effect because the UK leaves the EU. A simple stroke of the pen makes it valid until replaced by another licence. You guys seem to be enjoying and talking up the prospect of Aviation Armageddon come March 2019. There are too many vested interests to allow that to happen. Yes it is potentially messy but it will be sorted.