Sue,
Excellent points about the scenario and under different personal circumstances my answer would change. But I can't seem separate my reality from the scenario presented.
My variant of this includes my wife, son and daughter. My 6 year old daughter could probably hike out with me, heck she might end up dragging me along the last bit

. My son is older and has Down Syndrome with some mobility limitations and some other challenges so he probably won't be walking out, at least not without more supplies and support. Similarly, my wife has some mobility challenges due to foot surgery and a long walk over several days just isn't in the cards.
So while I think the hypothetical couple could walk out, I don't fit the profile and my answer is colored by that.
Good discussion and I keep learning so much here.
Thanks,
-Eric