You might consider taking a look at Celo. They have ultra-light client support [0], it's proof-of-stake with single-block finality, and they run a true EVM that you can program in Solidity. It's mobile-first but since it's fundamentally a fork of Ethereum it is also web3 compatible -- there's a metamask fork here that should soon be functional [1]. Gas is payable in multiple ERC20 tokens, and should remain cheap as the network scales. Not sure if this falls under your "ethereum killers that can do 10x transactions/second" so apologies for shilling if it's not interesting to you.

[0] https://docs.celo.org/celo-codebase/protocol/plumo

[1] https://github.com/dsrvlabs/celo-extension-wallet