Beaver, I agree there is some lack of clarity around the issue of where the operator resides and the associated implications of that. But practically speaking, the question that should be asked is whether the operator is resident in the EU or not. If they are, then EASA rules apply, regardless of the registration of the aircraft. If outside the EU...and the aircraft is not registered in the EU, then you escape...
The deadline for resident 3rd country aircraft to comply is currently April 2016, although NCC doesn't come until August. I suspect the April deadline will get pushed back again, but I can't be sure. Might be worth waiting until early next year, and if it doesn't get moved again, get skates on to be NCC compliant.
It's also looking like sub 5.7 twin turboprops will be excepted from compliance.