The upgrade treadmill is planned obsolescence applied to the human body. Each enhancement generation is designed to integrate so deeply with cognitive and biological systems that removal becomes more dangerous than continuation. You're not paying for an upgrade — you're paying to not be downgraded, because baseline human capability now feels like a disability after a year of enhancement.
The mechanism mirrors the SaaS model: your body runs on subscriptions. Neural processing, sensory enhancement, immune system optimization, metabolic regulation — all licensed, all versioned, all requiring periodic updates that introduce new dependencies. Each upgrade makes the previous version feel intolerable. Each new dependency makes the subscription non-optional. The person who chose to enhance their vision five years ago now literally cannot read without the current-generation optic suite — not because their natural eyes were damaged, but because their brain rewired around the enhanced input and can no longer process unaugmented visual data.
The Great Divergence (ST #9) describes the outcome — society split into haves and have-nots. The Upgrade Treadmill is the mechanism — the engine that makes the split irreversible. Those who step onto the treadmill can never step off without catastrophic capability loss. Those who never step on become increasingly unable to participate in a society designed for the enhanced. Both groups are trapped. The only people who profit are the ones selling the next version.