Today, we are familiar with a term Difficulty Retarget aka. Difficulty Adjustment which automatically executes after 2016 blocks that is about 14 days (2 weeks).
Well I wonder how Bitcoin difficulty adjustment will adjust itself once we have Quantum computing, that will target hard problem of every security algorithm/protocol. I know there are many IF and ELSE about Quantum computing and its no surprise as every new technology has to face some resistance initially. We need to have rational answer that why Quantum computing wont be affecting Bitcoin.