We have had this discussion a lot of times already, before super computers become a threat to BTC, we would have moved to an algorithm that is resistant to it. The development of quantum computers is a gradual process that will take a lot of years, it is not like we would wake up one morning and QC is set to break BTC, this gives the network ample time to develop a resistant algorithm.

However, take note that if QC is ever a threat to BTC's SHA-256 algorithm, then the threat does not rest on only BTC, but on a lot of industries, and BTC may even be of lower interest for attackers.