Thus if you, as an operator, are resident in the Community, you are required to have an EASA-Part-FCL licence even if you fly a foreign-registered aircraft. BillieBob has set out the (very limited) conversion and validation options
Sorry, but I don't agree. The 2008 Regulation is an enabling regulation and the devil is in the detail of the Regulations now published. If you look at Article 7 of the basic regulation it says:
The requirements of the second and third subparagraphs may be satisfied by the acceptance of licences and medical certificates issued by or on behalf of a third country as far as pilots involved in the operation of aircraft referred to in Article 4(1)(c) are concerned.
This reflects the current position in international law. It does not seem to me that any detailed regulations have been proposed with regard to the default position under ICAO, which is that Foreign non EU registered aircraft may be flown with the appropriate (non EU) licence for the state of registry of the aircraft.
That would be taken care of in a different way. In almost every country (I have researched this a little bit) an ICAO CPL/IR can get a local CPL/IR validation, or even a conversion, provided he has a relationship with a local commercial operator of aircraft registered in that country.
May be now, but not under the new proposals, I fear. Annex III applies and conversion is limited to getting a PPL.