Cool chart! Interesting to see how much of an outlier Bitcoin is. The middle tier currencies in this list (USDC, USDT, etc) are built on Ethereum, so once Ethereum finishes its switch over to proof-of-stake, both they and Ethereum will drop down to almost nothing in terms of power used per transaction.
We will see how proof of stake will work, and in FAQ is a paper about it. POS have one big problem, that you only have to buy coins once and stake them and you will get richer every day by doing nothing without any additional investment. Basically it will make rich richer and more centralized. We will see how it will works in future.
I think Ethereum's approach is interesting, because after 6 years of Proof-of-Work and several up and down markets, the distribution is widespread at this point. For example, even the co-founder Vitalik, only has about 300K of 115M circulating supply. So now I feel like they can migrate to proof-of-stake and it will not lead to excessive centralization.