Not to mention that when quantum computers become a reality, they'll be able to unencrypt all transactions in that blockchain, leaving your past open for anyone to see.
maybe that doesn't matter anymore by then?
The thing with quantum computers is, while they certainly can break todays encryption, they will also be able to create NEW ENCRYPTIONS to secure things even more.
What makes you think that once quantum computers are established they will not be made the biggest business sold to every household everywhere, as it has always been done with every electronic device ever?
I look forward to quantum computers or whatever new thing there will be in the next decades.
Free market enterprises will make trillions selling those devices to you and me and eveybody else.
I just hope there will be somekind of smooth transition, that will not make cryptocurrencies unusable