A quick though: why is family considered to be a basic building block of society? Family is fundamental to individual's life and wellbeing (unless you are a real lone wolf, gunslinger and a tragic hero), but... a family is usually not independent and self-sufficient. I mean, financially and when all is well, sure - if a family has enough money, it can hire help, buy everything, etc. But in usual cases when at least one adult has to work (or else they all will starve), it's a fragile self-sufficiency and unstable situation. Illness, accident, economy crisis, there are plenty of external factors that can render a single family incapable of supporting itself.
But, what then? Then it needs a strong State to provide it with the basics. Interestingly, the family unit is the most vulnerable and needs State most. Individuals have no dependencies, no children to support, not much to take care of, and big families are much more resilient - even if one member gets ill or otherwise incapable of providing, it's much easier to cover for him/her. Therefore the State will promote small families over individuals and bigger groups.
Economically - the smallest unit is targeted. Individuals and small families - when you look at ads in TV, they are very specifically targeted - lady of the house, man, father, all societal roles have their specific set of attributes and exploitable features that can be (and are) used by advertisement industry. And in bigger families stuff can be shared (what a waste of marketing opportunity, if ten people use the same washing machine!), and there can always be that rebellious person saying "why the hell you need that new phone for? what's wrong with your old one?"
Sooo... families are great (in an ideal world at least, I have great parents and parents-in-law, fortunately all of them, but there are moments when strangling one with the entrails of another seems like a healthy solution to the problems they create), but families are great from an individual point of view. They provide (should provide) support and stability, insurance, fallback, failsafe, safety net. Especially extended families with many different individuals bonded together by blood - or think of clans, tribes, small enough to know everyone (remember Dunbar number!), but big enough to provide redundancy (awful word to use here) and resiliency. And, given how little effort is these days required to grow food (aquaponics? hydroponics? aeroponics?) and create self-sufficient and independent households - this is the direction we should take.
A hundred people strong groups should be the very foundation not of one particular society, but of our species. This should be the basic building block. How resilient would be a nation build around such structures? Decentralized to the point of having zero government, and common infrastructure created on low-level mutual agreement between directly involved groups (who'd need thousand miles of pipelines, if all you need is electricity, and you can generate abundance of it locally?).
But then it would be harder to get our youngsters to go to war by thousands. And who would pay for all the missiles? And tanks? What a shame it would be if a nation could not send an aircraft carrier to bring democracy to some distant land...