Just as a point of reference there is no such thing as as a US Drivers Licence. Driver Licenses within the USA are issued by individual states, in a similar setup to that with Drivers Licences issued by individual countries within the EU. This could create a legal issue on FAA ability to regulate flying based on state driver licenses, but I for one really do hope they can eliminate the Class 3 medical for FAA PPSEL pilots.
I would imagine that this development would have no effect on foreign pilots flying on FAA Pilot Certificates issued on the basis of a foreign pilot's licence - seems to me they'd continue to need whatever medical their foreign pilot's licence requires.