This is what I expect will happen to Bitcoin in the event of a Quantum Computer powerful enough to 'kill Bitcoin'. A solution will be found and we will simply move on after a few minutes, hours or days of panic. That is it.
With the additional benefit that we 're kind of prepared for that, in a sense that we know it is possible, so we can take the proper precautionary measures (if that's a proper term).
In 2010, the bug was discovered out of nowhere.
That's not the case with quantum computing.