how does the bitcoin system handles 10k+ transactions an hour?
Alternatively:
https://en.bitcoin.it/wiki/Scalability#Increasing_Block_Size
https://blockchain.info/charts/n-transactions
It hasn't hit that limit [as of yet] for a full 24 hour period so there is no way to know if that is true.
But really, its only "unsolved" in the sense there hasn't been a need to solve it and so an arbitrary limiter [1 megabyte] has not been increased.
In practice transactions have multiple inputs and multiple outputs. Based on average size of recent transactions it comes out to ~2.3tps.
If I understand correctly, you're saying that this architecture might not only [possibly] not be cost-effective, but also effectively reintroduces centralisation and counterparty risk with the fixed miner pools as the SEC is needed to prevent AltExchanges from being manipulated or failing?
So it might not even be a solution to a problem the financial services industry (which throws millions at low latency connections for monitoring and executing trades but cares little about T+3 settlement) doesn't think it has?
Scaling Bitcoin requires everyone to agree on bigger machines/faster pipes and/or use the lightning option [which may or may not work]. Both of those options don't have the problem I stated.