That numbers adjusts upwards and downwards every 2016 blocks. So if we burned the entire planet the recipient will mine most of the bitcoin for a maximum of 20

That numbers adjusts upwards and downwards every 2016 blocks. So if we burned the entire planet the recipient will mine most of the bitcoin for a maximum of 2016 blocks at a faster rate than before they started mining, and then the difficulty will adjust upwards reverting the block creation time to 10 minutes per block. When the planet extinguishes, blocks will be found much slower or cease being found at all, until the end of the 2016 block period where difficulty will drop much lower, allowing people to earn bitcoin using an abacus and negligible amounts of power. So there is no absolute need for bitcoin to use a lot of power and it scales up and down.