Yep that could certainly work if appliances and cars have an option to say "have my dishwasher finish or car charged by 9am tomorrow" and it knows how long a cycle takes and picks the best time.

For anything real time it wont work - here in Australia we had a discount for a box that you connect to your air conditioner which would throttle back its use during peak, and a lot of people ditched it due to impact on their comfort.