Government by a council of elders. Government by old people.
There are many knee-jerk reactions to the prospect of greatly increased healthy human life spans, most based on mistaken beliefs regarding the technologies needed, or mistaken beliefs regarding the way the world actually works - economics, human action, incentives. Some people believe that longer lives will result in stagnation, which is actually one of the more ridiculous and improbably outcomes once you start to pick it apart in any detail. Human society is restless and changeable on timescales far shorter than current lifespans, and the reasons why are rooted in day to day human nature. Our ambitions operate on a horizon of a few years, and that wouldn't change all that much were we to live for centuries. We are driven to influence the world today, now, regardless of the years that lie ahead of us. So the fashions of this year are gone by the next. The idols of popular culture rise and fall with rapidity. The political and business leaders of this decade are gone in the next, displaced by peers. Even corruption and revolution on a grand scale are usually only a matter of a few decades, not lifetimes.
Nonetheless, rationality rarely prevails in knee-jerk reactions - so folk think of stagnation, even in the midst of this boundlessly energetic society we live in, packed wall to wall with constant, ongoing change. A subset of these beliefs on human longevity and stagnation involve the nebulous fear of a future gerontocracy, the rise of a self-perpetuating ruling elite of ageless individuals. Funnily, this is often voiced by people who are, unlike myself, perfectly comfortable with today's Western governments. I say funnily because I have to ask: are not our present societies already gerontocracies? Isn't any civilized society a gerontocracy? Who has had the most time to gather connections, a network, and make good use of them? The old. Who has had the most time to gather resources and invest them? The old. Who has had to most time to become truly talented and sought after? The old. Who has had the most time to work their way through a social hierarchy to challenge its existing leaders? The old. Where then will the elite and the leaders tend to arise? From the old.
Take a look at who just runs and influences companies, governments, knitting circles, successful non-profit initiatives, extended families, and so on and so forth for every human endeavor. Young leaders exist, but they are a minority among the ranks of the old. This is the natural state of affairs for any society that possesses enough technology to make thought and craft more important than strength and vigor.
All that is terrible in our present societies lies in the growing centralization of power, not the chronological age of those eagerly engaged in furthering the road to serfdom and empire. Even as power is centralized, there is still a year by year turnover of figures - even in the most defensible and corruptly secure positions of power and influence. They are largely kicked out by some combination of their peers and the mob in the sort of political anarchy that exists at the top, above the laws made for the little people. It is the rare individual who can stick it out long enough to be removed by the infirmities of age, even now, in this age of human lives that are all too brief in comparison to what is to come.
But back to the point. We live in a gerontocracy, and so did most of our ancestors. Yet change still happens just as rapidly as in past centuries when fewer people lived into later life in the sort of good shape they can manage today. Fear of some sort of comic-book gerontocracy emerging in the future seems, frankly, somewhat silly. But here is an article on the topic that treats such fears with a little more respect than I'm inclined to deploy.
The human lifespan is set to get increasingly longer and longer. And it's more than just extending life - it's about extending healthy life. If we assume that the aging process can be dramatically slowed down, or even halted, it's more than likely that the older generations will continue to serve as vibrant and active members of our society. And given that seniors tend to hold positions of power and influence in our society, it's conceivable that they'll refuse to be forced into retirement on the grounds that such an imposition would violate their human rights (and they'd be correct in that assessment).
In turn, seniors will continue to lead their corporations as CEOs and CFOs. They'll hold onto their wealth and political seats, kept in power by highly sympathetic and demographically significant elderly populations. And they'll occupy positions of influence at universities and other institutions.
So I asked James Hughes how society could be hurt if an undying generation refuses to relinquish their hold on power and capital. "Again, the question should be, how is society hurt when small unaccountable elites control the vast majority of wealth?," he responded. The age of super-wealthy is pretty immaterial, he says, especially when most of the people in their age bracket will be as poor and powerless as younger cohorts.
Hughes also doesn't buy into the argument that radical life extension will result in the stagnation of society. If anything, he thinks these claims, such as risk-aversion and inflexibility, smack of ageism and simple-minded futurism. "Seniors' brains continue to make stem cells," says Hughes, "and when we are able to boost neural stem cell generation in order to forestall the neurodegeneration of aging, older people will become as cognitively flexible as younger people."
As noted in my comments above, the historical record shows that people at the top are not all that good at staying at the top for extended periods of time. There are always outliers, but they are rare in comparison to the vast majority of leaders and the famous who are just part of the churn, coming and going, displaced and quickly forgotten once their few years are done. The top of a pyramid is a challenging place to stand.