Blockchain shouldn't include Proof-of-Work. Proof-of-Retrievability at least provides the same properties(paper: http://cs.umd.edu/~amiller/permacoin.pdf http:/

Blockchain shouldn't include Proof-of-Work. Proof-of-Retrievability at least provides the same properties(paper: http://cs.umd.edu/~amiller/permacoin.pdf http://cs.umd.edu/~amiller/permacoin.pdf impl: https://github.com/ScorexProject/Scorex-Lagonaki/tree/master/scorex-perma https://github.com/ScorexProject/Scorex-Lagonaki/tree/master... ). And Proof-of-Stake also could do the same under some assumptions(please see a new paper of mine http://arxiv.org/abs/1601.00275 http://arxiv.org/abs/1601.00275 ). Formal model of a lottery with anti-Sybil identity tools is definitely needed to shape borders.