A lot of micros already do that, with various levels of sleep, and lots and lots of i/o driven interrupts to wake up the processor when relevant data needs mana

A lot of micros already do that, with various levels of sleep, and lots and lots of i/o driven interrupts to wake up the processor when relevant data needs managed. What this ends up as is your processors main function sets up the proc, and then runs a loop that consists of little more than while(1) { sleep(); }. When some state changes that needs CPU time, it'll raise an interrupt, the interrupt handler will do what's needed, and the proc will go back to sleep. Micros have a lot of smart, low power peripheral processing available to them that helps keep power consumption even lower.