That's the conclusion I came to during the indoor experiment I carried out above. There was no distance information but as you say the heading and relative position could still be used to bring the aircraft back. But I guess you would need to have a GPS failure to be sure.
I suppose the fact that despite asking for information from anyone who has had a GPS failure to fill in the facts, no one has has come forward. So that must support the argument that a total GPS failure is remote. That, at least, is a pleasing conclusion.