Although of course it seems unlikely, all good things must come to an end and someday, in the distant future, the blockchain technology will fail. When it happens, what could replace it? Is there anything out there that functions similarly and just as good and reliable as blockchain? More importantly, if nothing replaces it, what will happen to cryptocurrencies then? Any ideas?
depending on why it fails, we may not need to find a replacement. we may just need to fix the immediate problem. for example, when ECDSA is broken, we'll just hard fork to a new signature algorithm, which shouldn't be too controversial because it'll fix a life-or-death protocol failure. that's why quantum computing isn't necessarily all that scary.