FUD.
You don't think the devs of a $150b asset would let it go to "0" do you? If anything like that starts to possess a threat to Bitcoin, there will be either a HF, or a quick fix but it will be fixed.
The difficulty is knowing when it will become a threat. Waiting until ECDSA is already broken is "likely a death blow to Bitcoin"
as Pieter Wuille opines here because of rampant key reuse on the network. If it's done as an emergency fork when the threat has already arrived, it may already be too late.
We should maximize the amount of time users have to upgrade to quantum-resistant outputs -- several years, ideally. The most optimistic estimates say ECDSA could be broken in 8 years. That means we only have a few years to implement a fork. There's been very little discussion on the mailing lists about this to date.