For now, I would be more concerned about hackers infecting my computer than about quantum threats in the coming decades. While technology advances quickly, it does not progress as fast as we might think. Additionally, if I were wrong and a quantum computer capable of breaking SHA-256 were to emerge tomorrow, it would most likely be kept secret for national security purposes.

Bitcoin would be the least of their concerns, as all modern communications rely on rsa ,ecdsa and others encryption methods.