The quoted argument is too simplistic and ignores feedback processes that would prevent reaching the catastrophic prediction. We can't predict 400 years so flippantly.

The population will most definitely not continue to grow (in fact it will start to decrease slightly the more countries reach "developed" status), and the energy consumption per-capita will also stagnate. After all, there is a huge difference between going from living in a log house to a modern apartment with utilities and AC, and not much of a difference between one laptop and a slightly better one some years down the line. Also, attitudes towards environmental protection are changing with the generations so we are likely making different decisions 50 years from now.