Most of the owners I know or have known are flying on straight FAA PPL/IRs.
Their options are
What the options for this around Europe?
Obviously the relocation options are strictly for the, ahem, people with special requirements in other areas (e.g. like lots of rain) 
The EASA PPL and IR and the medical can be done anywhere in Europe, more or less.
The HPA is more limited. The ICAO ATPL theory passes (1×FAA ATP exam or 14×EASA ATPL exam) are problematic and the 14x is a huge amount of work. I don’t think I know anybody in the “right age group” who has actually completed this stuff.
The Class Rating is even more limited. There is a French FTO which wants €20k.
Switzerland is part of EASA.
I think most are waiting. Which has been a good decision as we now have another extension.
How many pilots as in your title are there in Europe? 50?
Anyway, most are waiting it out it seems. The 2016 deadline will be extended to 2017. Quite possibly, this rule will never go into force. A revision of the Basic Regulation is already in the works.
For the rest: Converting from third country to an EASA PPL is easy. Converting to an EASA IR is very easy. Getting an EASA medical is often just a matter of throwing more money at your doctor. The HPA is a minor course. Re class ratings, I guess that pilots with considerable time in the respective aircraft will be grandfathered the EASA class rating. But I agree, all these things together make a bit of an undertaking. I guess most are waiting it out.
Norway is an EASA MS too. Ask me how I know 
Switzerland is part of EASA.
Norway is an EASA MS too
The wording in registered in a third country and used by an operator for which any Member State ensures oversight of operations or used into, within or out of the Community by an operator established or residing in the Community does refer to the EU. I don’t think Norway or Switzerland are in the EU… they may subscribe to EASA FCL but the reg has to be read as it is written, and “Community” = EU.
Which has been a good decision as we now have another extension.
Which extension?
How many pilots as in your title are there in Europe? 50?
It is also PC12, King Air, even the Jetprop. The TBM is just the one with the TBM Class Rating.
The 2017 extension.
Reference?
Euroga posts by bookworm. It is obviously coming.
The 14 ATPL theory exams are a red herring. They are not required by EASA for a Single Pilot High Performance Aircraft Type or Class rating. If you want to fly a MPA you need them.
