That has already been taken into account: the amount of energy used in mining due to the PoW algorithm would be so huge if the price continues to surge upwards, thus posing a problem not only for the infrastructure needed to be built but also to the end product of using all those energy. Switching to a new algorithm would be nice, albeit poses a different problem like the older one. It's a hard transition, but in order to balance everything, something needs to be done first. PoW wouldn't be around for the next 100 years for bitcoin. It will be replaced with a newer, more effective and efficient algorithm eventually.