A development of productive forces which would diminish the absolute number of labourers, i.e., enable the entire nation to accomplish its total production in a shorter time span, would cause a revolution, because it would put the bulk of the population out of the running.

This is the effect of automation.

It necessitates providing either alternative jobs for those workers to do or maintaining the existing jobs and decreasing work hours. These are your options, failure to do one of them will lead to revolution.