That's logical qubits though, right? All of these "announcements" are for physical qubits. Depending on the error correction used, it could take thousands of physical qubits just to make a single fully error-corrected logical qubit.
I don't think that it's possible to lower qubits number without optimizing an algorithm.
That 256 bit ECC key is worth a 3072 bit RSA keys. At some point though people with access to quantum machines will be able to break that encryption.
Bitcoin should die for many other reasons but I don’t think QC is what will kill it, I hope at some point rationality will. Crypto does represents just how broken our financial/economic system is and how easily you can push so much wealth into a non productive bubble.
You mean entire https web.
Financial+banking sectors would collapse? Or had to build private trusted networks? I dont even know what could be done.
The blockchain is in particular trouble because it's decentralized. Every wallet holder would have to re-sign their transactions with quantum resistant key pairs. But this is unlikely to happen to a good number of wallets (eg Satoshi's wallet), meaning a bad actor will crack the wallets that haven't done this one by one. They will then accumulate a truly ridiculous sum of Bitcoin and devalue it for everyone else.
In fact, if someone did develop a quantum computer, they'd probably not announce it - letting it passively crack wallets, slowly accumulating vast sums of wealth, and also decrypting communications at the behest of intelligence agencies. It will likely be years after the development of such a computer that we will actually know it existed.
There will be some deadline after which old wallets just will not work (essentially destroyed). So Satoshi's wallet finally will vanish.