Contradicting advancements in the Technology space
In today’s technology landscape, the blockchain promises unbreakable data security, but that will all be undone as soon as quantum computers come on the scene. Blockchain security is based on mathematical puzzles that are incredibly difficult for even the best conventional computers to crack. Example the SHOR's algorithm would be possible now with Q-world. How shall we plan in such a contradicting advancement in technology. Quantum technology presents a very real threat to any system that relies on mathematical algorithms for its security.
Yet another problem being the ability to mine quickly in a sudden quantum speedup could lead to destabilisation of prices and more importantly control of the chain itself — an unexpected quantum speedup could, if hidden, lead to vast centralisation of mining and possible 51% attacks.
Not far are the days where these ledgers would need endless soft-forks if not hard ones against the unforeseen cyber attacks. I don't think Bitcoin should be the choice of currency with such unpredictable threats of probable Quantum supremacy.