[TheOtherHobbes]

This has already happened at a higher multiplier.

An Apple Watch has more processing power than a Cray 2, but it uses a rechargeable battery instead of a 150kW power supply.

The problem is that cycles expand to fill the space available, so another 1000X drop in efficiency would mean new kinds of applications rather than being limited to affordable super computing.

While individual computers are far more powerful and use far less energy, the power consumed by computing on Earth as a whole is far higher than it was. (Not even counting energy vampires like crypto.)

There's no reason to assume that trend would stop. Displays could easily have much higher resolutions (possibly holographic), IOT could be truly ubiquitous, AI could be in everything, entertainment could be social, interactive, and immersive, and so on.