There is a bit of a parallel thread
here but I think the bottom line is that we will never get a truly bilateral version of what the USA does right now, over here in Europe, because that would enable all the European airline pilot wannabees to go to the USA and collect the FAA CPL/IR, or indeed the FAA ATP, at a much lower cost than doing it in Europe, and then come back home and convert it.
Given that most of these people are flat broke (they have to be to want to fly RHS on ~£25k, for quite a while) the decision whether to spend say 60k here or 40k over there would be a total no-brainer.
That would destroy the European FTO business, which is already creaking under the costs of propping up the various national CAAs (see Cabair etc).
There is simply no way, short of hell freezing over, that the EU will let that happen.
What could happen is a "free" EASA
PPL/IR, handed out to anybody with an ICAO PPL/IR or CPL/IR, by sitting an air law exam and a flight test. That is the fairly standard procedure around the world for validating foreign CPL/IR/ATPL papers to local CPL/IR/ATPL papers, so you have that precedent already. But the EU can't do that, for straight protectionist reasons.
The air law exam serves the obvious piece of meat to the regulatory dog ("our air law is different to the USA's") notwithstanding the fact that the JAA CQB air law questions are nearly all utterly irrelevant bollox (e.g. the masses of ATC-type runway separation questions from the Portugese ATCO who got the job of writing it).
The flight test similarly verifies the pilot can fly.
And the loss of FTO income would be pretty small.
But I don't think even that will happen, because the FTOs must already be sharpening their pencils, hoping for a torrent of Euro resident PPL/IRs and CPL/IRs about to be shafted by EASA, turning up on their doorstep. This won't happen because the 2014 derogation is likely to be extended past that date anyway, etc. Almost nobody, as a % of the total potentially affected population, is doing the conversion route at present.