Ethereum's Proof of Stake "beacon chain" is already live, with around $6 billion staked (since launch in december 2020). Next year is just formalizing and testing it taking over from the miners. So despite timeframe, there's little uncertainty about the outcome.
https://beaconcha.in/ is a nice explorer to see beacon chain running live.
OTOH, it could be cracked tomorrow and value of dedicated silicon will go off a cliff. So I don't blame the GPGPU crowd for that, before even considering the engineering challenges of silicon/FPGA for eth.