All flight plans have that Glueball, as well as multiple redundancy on the aircraft (not to mention crew cell phones). But as Alexban says it could happen.
So back to my question - does your flight plan alternate route/altitude allow you to divert as per flight plan in that scenario? The routing is not the problem - the altitude is the grey area.
What I'm looking for is a reference in JARS, CAA or FAA that states so. I've been unable to find any guidance on this matter as all loss of comm procedures seem to assume that you will land at destination.
Maybe someone from ATC could jump in here.