As soon as Quantum computing becomes cheap enough all hell is going to break loose when it comes to public key cryptography.
I've heard people say this before, but can't we just add more encryption bits? True, 256-bit, 512-bit is too low. What about a million bit encryption? Quantum computing will only be a problem if just a few people have these computers. If they are mainstream then there is a level playing field once again.
Yeh ! what you say would work, but the problem is that for such computing power to reach the masses, will take a long time. an estimated point would be some where around 30 years. Till that time the government or companies that have the most money, would be the ones able to afford it.
We already know that google has just got their first Quantum computer. If google can get it then there is nothing stopping Big government getting it. Even if we say the governments will take another 5 years to acquire a quantum computer, that still leaves a huge gap of about 10-15 years that government/companies can use their Qcomputers effectively.