Actually, Granny Gums is probably one of the most valuable members you can get – doubtless she’ll probably know how to cook on a fire, have ten uses for every item, can darn clothes and has lots of entertaining stories for the kids…
I agree, this will be the case for the next few years as long as the pre 1950 generation is still around. But most people born after 1950 probably know little old time skills, especially if they grew up in a city.
I think one of the biggest assets older people bring to groups is their wisdom and usually resilience because they have simply experienced a lot more than younger people.
They can become a center of calm and this can have tremendous effects on the whole group.
About family units. I see in Asia every day how great families stick and work together. Here few people expect any help from the government, instead your own family is your safety net. Very good for survival scenarios because they just stick to the same people they did all their lives.
Alea iacta est ("The die has been cast")