This is all heresay, what isn't on this Subject.
It will be 4-2-1.
It will apply to new registrations only, existing vehicles will remain 3-1-1.
New items will be added to the test to meet a euro minimum standard.
It will happen soon.

I expect there is some euro legislation somewhere detailing exact requirements, if not I would bet money on it appearing soon.

Can't see this having a major impact on what we do, possibly lead to a more involved(higher cost) test. Eventually most of the euro standards will probably apply to all vehicles