hand warmer, companionship and pest control.

They are also pretty self sufficient, unless conditioned not to be by being pampered.

I would assume that apart from morale boosters and possible extra warmth, cats would be of much greater good at some type of long term homesteading-kind of survival.

If you have a long(ish)-haired cat, they tend to shed enough hair for you to be able to handspun enough yarn annually for a set of wool hats and mittens if not a full size wool shirt. The yarn is really warm but really hard to get even and quite weak if not mixed with other fibres as the hairs are slippery.

And if you comb the hair off of them they won't even decorate your carpets with furballs of their own.