“Even if quantum computing posed a threat to the cryptographic layer, Bitcoin’s decentralized and global network of nodes would play a critical role in driving a transition to quantum-resistant algorithms—an advantage centralized systems simply do not have.” 

What transition? We have nothing ready. If someone proved they could use quantum computing moving coins they never had a key to, like Satoshi’s coins, price of Bitcoin would fall 99.99% within a week. If we not gonna have a procedure ready, for quantum attack, Bitcoin will die following such attack. People wouldn’t trust it ever again.