Energy depletion? We lived through a time when renewable energy was just a twinkle in our environmentalist eyes. There is no human history from 10k years ago, a lot of interesting paleo-anthropological speculation though, some of which points out that our paleo ancestors were richer in free time, family time, cultural time than are folks in “modern” countries today. Living standards are a hugely subjective measure. Will we all live in 5000 sf mini-mansions and drive huge gas guzzling SUVs in the future? Probably not. Will we learn to live in balance with the planet, distribute our vast wealth so that none live in need? Certainly possible. Largely up to our creativity, which when empowered by human enterprise and free markets can either flood the atmosphere with CO2 or perhaps build smarter societies.