How is easy enough. When is the more interesting question.
Nobody will ever know it's possible to crack everything until it has already happened. To guard against it you'd have to hard fork the entire planet. Humans really aren't very good at preventative measures. They tend to wait until the last minute, but in the case of that preventative is the only way of stopping everything from turning to dust.
What do you exactly mean by "How is easy enough"? If it was that easy, some bright mind would've already figured out a way to protect bitcoin from quantum computing right?
We must also take into account that quantum computing isn't a thing yet. So perhaps as we learn more about quantum computing we can also figure out ways to protect bitcoin from potential treats. Maybe that is what you mean by figuring things out last minute?
I think he meant that there's already a lot of work going into developing quantum resistant algorithms, even NIST has work to identify and recommend the best algorithms for this since it isn't a challenge unique to blockchain. There are algorithms that should be resistant to quantum computing attacks so presumably Bitcoin would need to switch to one of these algorithms. That is an over-simplification though because what happens with all those coins sat in storage that were generated with the old algorithm. It may be that the only solution is to start a whole new blockchain and there are altcoins out there that are built to tackle this exact problem.
