[silverlake]

Health care: the network of providers and insurance companies need to share limited information securely. Right now it's completely ad-hoc and broken (I was billed $3000 for a cancer drug. I had the flu!)

Identity/reputation: If you have a certain reputation on eBay, you can't carry that reputation over to Amazon to sell goods. You must start from scratch. If the reputation score was independent of the service you could even post it on Craigslist and people could trust it.

Real estate: I paid a lot of money for a completely useless title insurance. If the details of a home title were stored on a blockchain, there would be no need for this entire industry of bloodsucking leeches. :)

Supply chain: there's an ad-hoc network of suppliers for many things (cars, planes, electronic doodads). There is no central authority, and it spans the globe. Having perfect knowledge of the supply chain can save companies lots of money. It's what made Walmart successful, now everyone can do it on a shared platform.

The tech for this stuff is still very primitive. I'd compare it to when Jaron Lanier started virtual reality in the late '80s. He was right but several decades too early. There are still some limited contexts where a current blockchain can be useful right now, but it won't be a big thing for a while.