The Ethereum protocol support team published a blog post, announcing that Klin testnet is in the process of launching. Kiln is supposed to be the last merge testnet of Ethereum to switch to the Proof of Stake consensus model. The blog post explains that similar to the Ethereum mainnet, the execution layer of Kiln initially went live under Proof-of-Work along with the Beacon Chain running Proof-of-Stake. Kiln is supposed to move completely to PoS till March 17.
At present, developers, node runners, infrastructure providers, and stakers can test on Kiln to make sure it will transition seamlessly on public testnets.
The prior merge testnet, Kintsugi went live on Dec. 20, and it will be deprecated in the next few weeks.
It's uncertain when the final PoS transition will occur. The team says it will be possible to estimate the launch date when clients finalize details of implementations and Ethereum testnets such as Goerli, Ropsten, and others will run through The Merge successfully. The final step will be the merging of the Eth mainnet with the Beacon chain of the ETH 2.0 system.
Ethereum's major upgrade will enhance the network's capacity to process transactions, allow lower fees and make the blockchain more sustainable. Unlike PoW, which requires solving complex mathematical puzzles to produce new coins, the PoS model will allow Ether holders to stake their coins to implement transactions, produce new blocks and earn rewards. Currently, the number of staked ETHs in the ETH 2.0 contract is above 10 million.