Concern about the impact of technology on the value of human labour is nearly always posed as a recent phenomenon. – "Will a computer take your job?" But this is mistaken, since wealth has been created in a predominantly systemic, non-human, fashion for a very long time, increasingly so in the West from the 1200s onwards at the latest. Earlier societies will have seen the process start and stall, alongside sustained growth. Indeed, the declining value of human labour is closely related to the onset of sustained growth, and is probably part of that phenomenon. The writings of Marx, socialism generally, the socialist version of the labour theory of value, all are fighting a rearguard action.
As human labour becomes less and less important both individually and in aggregate to the creation of wealth, politics becomes correspondingly more important, and crucially so once the distribution of societal wealth cannot be left to an approximate determination according to apparent contribution (wages). With politics, modern, all-embracing, all-obsessing politics, the world returns to a status society. Liberalism, then, can be seen as a temporary arrangement appearing in the phase between the stabilization of sustained growth, the 1600s to 1700s in the Netherlands and Britain, and that point where the contribution of most individuals or all in aggregate drops below a level where it is no longer missed when absent, from 1750 onwards, and with increasing clarity from 1850 onwards.
This process is confused in detail by the fact that the nominal and apparent value of labour will be artificially preserved as the visible part of the fairing enclosing that societal mechanism where income is assigned by status. There is a great deal of lag, illusion, and momentum in this matter.
Blowing the smoke aside, we can see that the advent of extreme mechanisation is not a discontinuity precipitating a crisis in society. – It is the latest substantial increment in a process long established, and for which human societies already have remedies and modes of address.
Many, perhaps all of us, are prone to pretend that humans are more valuable to each other as sources of wealth than can easily be justified, this economic fiction being ceremonially useful in dressing an assignment of income that is actually determined quasi-administratively by status. Hardly any of us are net producers.
We can conclude, therefore, that nothing much will really change in the face of more computers and machines; new ways will found of pretending that each and every human contributes substantively and indispensably to the creation of wealth and is therefore rewarded proportionately on that ground. We are already pretending that humans matter; we will go on pretending, only adding more stage business, rhetoric and costume.
A disturbance to this pattern may occur when men and machines compete for resources. To a degree this happens now, in investment choices favouring "plant" over "parlours", but men are still, as far as I can tell, in charge of the allocation and do so to maximise returns to men in the long run. If machines start, perhaps they have already started, to influence allocation in order to maximise returns to machines not men, then something interesting and genuinely threatening to the human species will have happened. Like so many other important changes in systemic societal character, I am prepared to bet that this will creep up on us, if it happens at all.