Whatever probability you assign to Q-Day occuring in the next 3 years, is the same discount factor you now need to apply to the value of Bitcoin today. It will take at least 1 year to get consensus on a Bitcoin upgrade and 1 year to fully deploy that solution. Collectively 2-3 years to upgrade Bitcoin. So if there's a 10% risk of Q-Day in 3 years, you need to discount the terminal value of Bitcoin by 10% today. Until we get consensus on a Bitcoin upgrade, the terminal value of Bitcoin declines every day, as the Quantum threat rises.(Charles Edwards)