Which is of course exactly the same that would happen if you were flying a route based on
any single navaid that suddenly failed (more like went out of range).
Knowing that doesn't make it any less unpleasant of course, but planning for it (eg keeping a simple time-speed-distance log) can mitigate the effects somewhat...
I well remember the second check I did in the GPS equipped aircraft I used to fly, checker turned off the GPS and said, "It's failed". Took me a while to get my head around that! But really it shouldn't have.
(I was about to add, at least in a Dauphin you can stop and have a look around, but then I thought, hmmmmm, low level helicopter in a jungle, better not stop methinks
)