What block size for Ethereum's blockchain would be required to hit 56,000 tps? I'm really getting some deja vu in having to write this out for the millionth time in a 18 month period.

None of your talking points magically address the extreme costs of prerequisite physical infrastructure needed to hit 56,000 tps.

Bottom line, it's impossible to match the throughput capacity of just a single credit card company on any blockchain, be it Bitcoin or Ethereum or BBQCoin, without incurring enormous costs in terms of CPU and bandwidth. This is to say nothing of doing decentralized exchanges, order matching, and option contracts - all of which Ethereum has been advertised as doing on a blockchain. For that you'd need hundreds of thousands of tps.