Good question 😉😉😉

Well first quantum computers are as bad at solving brute force sampling problems as regular computers are. Just think about it: you‘d need to sample numbers in a 256-dimensional space.

With a quantum computer, it may happen that your private key can be cracked in a suboptimal sense (what we call NP-incomplete), meaning I can approximately guess a small volume of the parametric space that contains your key. But (1) it will take decades of brain power to write clever algorithms for quantum computers and (2) we can always introduce a new private key standard such as SHA512 and even more complex to keep the security standard high.