Technical and philosophical uncertainties aside, I don't thing a blockchain is a suitable medium for humanlike consciousness. A blockchain exists to lock down a state irrevocably, and state changes are encoded in new blocks referring to the old ones. If you think the Bitcoin blockchain is bloated. just try storing every neural operation in one... Besides, neural rewiring, malleability of memory etc. seem like pretty important parts of being a live person to me.

We'll just have to do with our memories of those lost for now.