Broadly speaking blockchain only solves a singular problem: Trust. If there is some work that needs to be done between parties and you don't trust the parties involved then you can use blockchain to do the work in a trust-less setting. This is why money has been the first and most prominent use case; people are less trusting with their own money. For a specific non-money potential use case of blockchain I would say i…
Okay so with a bit of hand-wavey stuff I'm sure we can make a parallel where you also solve world hunger with blockchain and trustless systems where there are no centralized parties that can do bad things. But realistically, how would this work? Whose key will end up signing the TLS certificate for my website? You're not really proposing anything more concrete than "let's move CAs to a blockchain".