But you would still need an authority that can unilaterally make changes to these ownership records. People die, things get lost, stuff happens. So it can’t all be based on signing with private keys of individual persons. At that point: Why not run a central database of it all. It’s cheaper, more efficient and you could still publish a public record for traceability.

I really don’t see any problem that Blockchain could solve better than other solutions. Except Cryptocurrency.