What if Western Civilization is at Peak Power Production/Consumption?

An average healthy man can produce about 200 Watts (<1/3 of a horsepower) of mechanical power for a sustained period of time. Highly trained athletes can produce about twice that amount for a sustained period. The main limiting factor in the ability to produce power is the rate at which oxygen can be absorbed by the lungs and distributed through the body to working muscles. That's the so called "aerobic capacity".

It's pretty reasonable to assume that entire nations and economic systems have secret limits to their ability to produce power and energy, too. Right now, the western economy/energy system produces around 10 kWatt per person 24 hours a day all year round. It's possible that's an inherent limitation imposed by Earth's available resources and their distribution around the planet. Only so much energy can be delivered per second.

That might be the case even if new energy sources become available, e.g. nuclear fusion. Even if fusion power is someday feasible, it might have built in limitations such as the duty cycle of the reactor, or limits of materials to withstand heat or intense radiation. Similarly, the electric grid can only support so much power, and so on and so on.