I'm not sure about another order of magnitude. Yes, 5 lightning TXs for an individual is a lot, but this is an average, so for an exchange (”Bitcoin bank”), that's nothing.

Shared UTXOs may be able to help. I'd love to see more development going toward channel factories. However, if unilateral exit and constant communication are required while fees are high, it seems that a shared UTXO has a high trust threshold, which will make it impractical.

I'd love for you to be right that >100,000,000 entities will regularly transact on-chain, but I fear Saylor’s estimation of 100,000 is closer to the current trajectory. I'm working on an e-cash solution for close friends and family to share a lightning node to get closer to my optimistic 10,000,000 estimates. If trust is required, it's better to be at a lower/smaller organizational level than a company or government.