Does Bitcoin survive in a Quantum Computer world?

In the spring 1925 Werner Heisenberg was lost in thick fog and was unable to find the path trekking the mountains of Helgoland island off Germany’s North Sea. As he climbed the fog grew thicker but glimmer’s of light became brighter and eventually reached a peak perching himself above the thick fog. Heisenberg’s experience of light glimmering as he ascended led him to challenge the prevailing idea that classical physics applied to the world of atoms. Born was the idea of quantum mechanics. And almost 100 years later quantum computers are here and, at scale, present a challenge to emergent technologies such as blockchains and cryptocurrencies.

Web3 is driven by the decentralisation of computing and the novel application of cryptography for secure transactions in a trustless system. However, the rise of this hazily defined Web3 is threatened by the prospect of quantum computing.

Blockchain, or open distributed ledger, consumes the same amount of energy as a small country simply to exist. The blockchain is not the cause of the large energy consumption but the programmatic governance - Proof-of-Work - determined by the technology that sits on top of the blockchain. In order to write new transactions to the blockchain, Proof-of-Work miners are the validators adding new blocks of transactions to the blockchain network. Proof-of-Work miners are incentivised to maximise their computation power.

Proof-of-Work is said to be unviable long-term because of the ever increasing energy consumption for miners to stay competitive. Quantum computing promises to change the long-term viability of Proof-of-Work:

Whether transitioning to quantum computers is economical or profitable is another question however it theoretically will solve the energy computation required for mining competitively.

Quantum computation is not predicted to exceed conventional computing, in terms of hash rates, until 2045 to 2050 but it's hard to imagine or know where cryptocurrency will be. It could be obsolete.