@forest, that question was not mine anyway. But I thought that if it was edited to be specific enough, it would be an interesting question. Basically by "blockchain" nowadays people mean "decentralized distributed ledger". Everything relies on consensus algorithms to make sense, because there's no authority. And the security implications of such algos are a matter of INFOSEC, IMO.
But you might also be right... since useful applications of "blockchains" are basically non-existent (yet, and will probably never exist), such questions might be considered too speculative here.