PRNAV could become the killer threat to IFR GA, because most currently fully IFR planes cannot be approved under the present regime (or anybody's understanding of it). I went to a Eurocontrol nav workshop last year and nobody there could agree on what it was about.
In the USA this will not be an issue because the FAA would never do anything so barmy...
A while ago I spoke to a very senior NATS ATCO whose view was that PRNAV is a load of bollox. He said that any plane flying on GPS, especially on autopilot, will easily meet PRNAV lateral accuracy (which is obviously true) and the rest of the stuff is going to remain tactically radar managed for the foreseeable future. It seems to me that Europe has turned PRNAV into yet another job creation scheme, deliberately obfuscated to keep it that way.
There are a few airports in Europe with PRNAV SIDs/STARs but currently all of them have some non-PRNAV (either RNAV, which "merely" requires BRNAV IFR GPS approval, or conventional navaid-defined) SIDs/STARs. I am sure this is necessary for compatibility reasons because the majority of jets (counting exec jets in that) flying around the place are not PRNAV approved. If this changed, those airports would instantly become out of bounds.
However RNAV itself is becoming very common at bigger airports. These SIDs/STARs cannot be flown without BRNAV approval, though to be fair one cannot legally fly enroute above FL095 without that anyway... Just noticed that Prague LKPR has gone all RNAV except one procedure.
RNAV transitions is another one. Look at Austria LOWW; plenty of those. Some IFR BRNAV GPSs, my KLN94 included, don't have these in their database and according to Honeywell never will have. There are various work-arounds e.g. entering the waypoints (which curiously are in the database). I don't think any of the x30 Garmins have an issue with this.
Back to PRNAV, anybody doing a major avionics refit must make PRNAV approval a condition of the contract.