That's still enough to enable IFR services outside of any kind of airways.
Apart from an IFR departure from an uncontrolled or no F -airspace airfield - and no IFR in uncontrolled airspace altogether.
Here in Europe, once you are "cleared to", if you subsequently suffer a comms failure, you are entitled to fly the filed route and land (at the filed ETA etc etc). But if you don't suffer a comms failure, you can't necessarily do that
I don't see the ambiguity to be honest... if ATC can`t reach you, then they can`t alter the clearance....