Side-rant pet-peeve: People who try to rescue the reputation of "Blockchain" as a promising way forward by saying its weaknesses go away once you do a "private blockchain."
This is equivalent to claiming the self-balancing Segway vehicles are still the future, they just need to be "improved even more" by adding another set of wheels, an enclosed cabin, and disabling the self-balancing feature.
Congratulations, you've backtracked back to a classic [distributed database / car].
Going off on a tangent: the blockchain people have paid my salary for a few years now, and I still don't own any blockchain assets.
I do like the technology for its own sake, but I agree that it's mostly useless today. (At least most of it. The part of blockchain that's basically 'git' is useful, as you can see with git. Ie an immutable, garbage colected Merkle-tree as a database, but you trust that Linux Torvalds has the pointer to the 'official' Linux kernel commit, instead of using a more complicated consensus mechanism.)
However there's one thing that's coming out of that ecosystem that has the potential to be generally useful: Zero Knowledge Proofs.
Yes, what Zero Knowledge proofs give you however is composability.
Eg suppose you have one system that lets you verify 'this person has X dollars in their bank account' and another system that lets you verify 'this person has a passport of Honduras' and another system that lets you verify 'this person has a passport of Germany', then whether the authors of these three systems ever intended to or not, you can prove a statement like 'this person has a prime number amount of dollars and has a passport from either Honduras or Germany'.
Where I see the big application is in compliance, especially implementing know-your-customer rules, while preserving privacy. So with a system outlined as above, a bank can store a proof that the customer comes from one of the approved countries (ie not North Korea or Russia etc) without having to store an actual copy of the customer's passport or ever even learning where the customer is from.
As you mentioned, for this to work you need to have an 'anchor' to the real world. What ZKP gives you is a way to weave a net between these anchors.
Honestly the Segway had a couple of useful effects, none of which involved the Segway itself becoming useful or popular.
1. The self-balancing tech spread to a variety of more interesting and cheaper "toy" platforms like hoverboards and self-balancing electric unicycles.
2. They encouraged the interest in electric micromobility, leading to, especially, electric scooters (which are simpler, cheaper, and use less space) becoming widespread.
This is kind of like the point someone else made that the actual useful thing the blockchain craze produced was "cleaning up your database schemas with the idea of putting them on the blockchain, then never putting them on the blockchain".
Side-rant pet-peeve: People who try to rescue the reputation of "Blockchain" as a promising way forward by saying its weaknesses go away once you do a "private blockchain."
This is equivalent to claiming the self-balancing Segway vehicles are still the future, they just need to be "improved even more" by adding another set of wheels, an enclosed cabin, and disabling the self-balancing feature.
Congratulations, you've backtracked back to a classic [distributed database / car].