Is there a way to do what you're suggesting with identities? I don't think there is. How are you going to rotate keys without a master key?
And even if you're ok with the master key, the only way to solve this without centralized providers is with blockchains. A blockchain for rotating keys doesn't make sense.
But I do want to know if you're ok with a master key and subkeys that can be rotated.
“Is there a way to do what you're suggesting with identities”
There are certainly solutions, but I don’t know what the best solution is, hence why I called it an open problem.
An example solution would be something like having your identity be a hash of your initial public keyset, making each key have a set expiration date, adding new keys by signing them with one of the existing keys, and then storing all of the rotation operations in a transparency log.
“the only way to solve this without centralized providers is with blockchains”
That’s not true; you probably want a transparency log, but that doesn’t require blockchains.
And even if you're ok with the master key, the only way to solve this without centralized providers is with blockchains. A blockchain for rotating keys doesn't make sense.
But I do want to know if you're ok with a master key and subkeys that can be rotated.