Hasn’t PoS been something “in the works” for ETH for something like 6 years now[1]? I don’t think anything guarantees its delivery in early 2022, it all seems like hopeful speculation until they deliver something.
This time it's very different. There are billions of dollars of ETH locked up in the staking contract, and proof of stake has been live and operating on the beacon chain for many months.
it took a long time to work it out, but it is running on the beacon chain and the consensus upgrade spec has now been merged: https://github.com/ethereum/EIPs/pull/3675
[1] This stackexchange question dates back to 2016, the earliest evidence I could find of ETH proposing PoS. https://ethereum.stackexchange.com/questions/9/why-does-ethe...