Google's Quantum Computer - Image Source
Google has recently achieved quantum supremacy. As per the popular science journal Nature, Google's quantum computer can solve complex problems in 200 seconds. As per the Google scientists, the world's fastest super computer will take 10,000 years to produce such results. It is really a revolution in data science and data processing. With Google's current achievement, it can be assumed that mainstream commercial adaption of Quantum computing is not far away. As per the reports, Google's first clients of Quantum computer will be Daimler and Volkswagen and they should be using this in 2020.
A Quantum computer are extremely different from the classical computers and it works with complex rules of physics. So, a Quantum computer is able to produce multiple range of solutions of a given problem at a time. And performance of such system grows exponentially.
Now a Quantum computer can technically crack encrypted data as per Shor's algorithm. Can it hack bitcoin network? Due to its ability to solve extremely complex problems in seconds, it is possible that a Quantum computer will be able to know the private key of a wallet just by getting the public key. So it may be able to hack an user's wallet. Due to its massive speed, it may also dominate other mining nodes and attain 51% of network's hash rate.
Yes, it will be immaturity to draw any conclusion. Quantum proof encryption technology is also being heavily researched and blockchain technology is also developing continuously.