below 10,000 anywhere east of the Rockies you will always be in cell phone range.
The original poster was presenting a scenario in US airspace so perhaps that is what you are refering to....but in Canada, that certainly is not the case!
As for lost comm, the reality from every controller I have ever spoken to is once "lost comm" is realized by ATC, they are going to end up sterilizing all airspace at the destination aerodrome (once you're anywhere close) until you're on the ground regardless of what might have been filed in a flight plan.