It will be better to create a quantum resistant layer to an existing blockchain protocol to increase its security or create a quantum resistant blockchain from scratch. They are the recent approaches.
The consensus seems to be that Bitcoin should implement quantum-resistant cryptography sometime before these threats become real:
Here's a relevant paper that speculates about when ECDSA will be broken: Quantum attacks on Bitcoin, and how to protect against them
Wasabi Wallet creator nopara73 believes 2022–23 is closer to the mark:
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The elliptic curve signature scheme used by Bitcoin is much more at risk and could be completely broken by a quantum computer as early as 2027, by the most optimistic estimates.
Wasabi Wallet creator nopara73 believes 2022–23 is closer to the mark:
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For Bulletproofs, what matters is the Shor RSA2048 line, which is predicted to be broken in 2022–23. In fact, ECC is more vulnerable than RSA in a post-quantum world, so our discrete logarithm assumption may be broken even sooner.
As you can see, we are beginning to approach the estimates at the lower bound. At the same time, those estimates are based on a boatload of assumptions that may turn out false. It may be wise to wait and see how quantum technology progresses over the next year or two before rushing any major consensus changes.
