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Advances in mathematics/computing will make these calculations feasible after decades at most.
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What calculations? Brute force? No, you are mistaken. Brute force of 256 bit will not be feasible.
In this case: calculations of ECDSA private keys. Most probably by using weakneses in algorithm, not by a blind brute force. The result is what matters.
Do you really believe that after 30-40 years secp256k1 will still be considered secure?
I'm not even a mathematician, just devil's advocating. What about using Shor's algorithm to narrow the timeframe?