On authentication - or rather, authorization, it's usually not relevant to establish identity ass opposed to access rights - I strongly feel this should build u

On authentication - or rather, authorization, it's usually not relevant to establish identity ass opposed to access rights - I strongly feel this should build upon cryptographic decentralized identifiers - on registration, send the service a signed number of your choice. You can now sign in on future visits by signing messages with the same key. No e-mail or phone number needed (but can still be requested by the service, of course). We're kind of seeing this by a second-order effect in the Ethereum dapp space, where you need this functionality to interact with the blockchain etc. Every user has some form ow Web3-compatible software, most commonly Metemask browser extension. I think it's an interesting ground where this could start spreading - the key infrastructure etc are already in place! (And in case anyone gets confused, it can be used perfectly fine without actually transacting to any blockchain or holding any cryptocurrency - it's just normal elliptic curve keys with easy-to-use APIs)