Do you mean "crack" instead of frack?

"crack": all coins
"fracking": only 'shalecoins' - see deifinition: https://bitcointalk.org/index.php?topic=5134441.0

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..if the private keys can be obtained so fast.

It will start slowly but the BTC community will then know that these 'shalecoins' are being 'fracked' and sold until there are no 'shalecoins' there.

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However, even this won't be the end of crypto per se, since even nowadays there're already some (at least, allegedly) quantum-resistant cryptos.

Yes, you are right. This will be the new beginning.

But thereafter 'shalecoin' https://bitcointalk.org/index.php?topic=5134441.0 will be solved and the blockchain will be clean.
That is important for the Bitcoin development.