Whether or not one can carry on with one's FAA IR surely rests on whether N reg will still be allowed to be based in the EU; EASAs thoughts on this seem less clear...
That one at least appears easier to answer - which is Yes, provided it is a piston SE or ME, or a SE turboprop. ME TPs and jets are variously screwed; they will be able to remain long-term parked here provided an EASA MO gets variously involved in their maintenance.
Here
Regarding the 2008 FCL proposal, I would always defer to better brains than mine to work out the full interactions of the different bits. Very few bright people I know can work it out.
Many very bright people are absolutely convinced those provisions refer only to license
conversions which is a completely different thing (and only relevant to people who want to fly EU-reg planes, typically IFR, but have only an ICAO non-JAA IR). And sure enough that is how it reads, superficially... this may have been intended by EASA because it is not in their interest to make such an aggressive measure too obvious too early on in the process.