I doubt that's going to scale if messages have to pass through the Ethereum blockchain. Most cryptocurrencies today are limited by their transaction volume cap

I doubt that's going to scale if messages have to pass through the Ethereum blockchain. Most cryptocurrencies today are limited by their transaction volume capacity because every transaction needs to be distributed to every other node in the network - In other words, the Blockchain workload is serial (limited by processing speed not concurrency) and cannot be parallelized (distributed is not the same as parallelized). It's not possible to have a single blockchain handling more than a limited number of transactions/messages per second - This is a hard mathematical law, not a hardware resource limitation. Sure, they can batch messages together to reduce transaction count (assuming they'd be willing to do that) but that only buys a bit of extra time. Looking at this I get the feeling that the Ethereum blockchain is doomed - It will be death by spam.