i'm not speaking about using the qunatum computuer to have the majority of mining power but about cracking somone private key after the public key get out (the public key of an adresse is public whenever you send money from it to someone )
so effectivly when those computuer are out you should alwayse use a bitcoin adresse to store bitcoin as long as you never send money from it
edit : unless the bitcoin change to another algorthime for the adresse keys
Do you mean that the private key might be brake in the future?
Is this mathematically could happen!
Thus the theory of cryptocurrency could collapse .
they could just change to another algorthime for the adresse keys if that happen but still if could impact bitcoin if the change is too late
you can read more here
https://bitcoin.stackexchange.com/a/49488