Yeah, these seem like impossible hurdles without a centralized identity system to fall back on. The good news is that we have several: FB, Twitter, etc. These centralized networks already pour tons of resources into identity verification- IE, the 'verified' tag on Twitter.

The combined reputation from many of these services could act as a badge of trustworthiness on the blockchain. You just need a system like Keybase to cryptographically associate accounts to a public key.

I have been shocked to see so few crypto solutions integrate with Keybase as a trustworthy identity network. I wonder why people aren't doing this?