Say the consumer needs of humans are food, clothing, shelter, transportation, communication, sanitation, education, healthcare.
Say specialized, relatively dumb machines are developed to perform all steps necessary to provide those requirements, without human interaction: mining, refining, manufacturing, planting, harvesting, distribution, fishing, construction, disposal, and so on.
Say machines exist to build, maintain, and repair themselves and all other machines.
At that point, the world is automatic and mechanized enough that all humans can be idle consumers only, and not employed producers.
If population growth is then restricted to less than zero, either through deliberate human-instigated or machine-instigated policy, or because of some disaster, hasn't the transition from humans to machines then been achieved without superintelligence ever happening?