It's currently estimated that 13 million qubits are required to break 256-bit encryption within 24 hours. Our ability to create a 13 million qubit computer is realistically beyond our 10 year horizon, so we can ignore it. This is the exact opposite of "be very afraid."

Do these probabilities mean anything at all?

  When Mosca and his colleagues surveyed cybersecurity experts last year, the forecast was sobering: a one-in-three chance that Q-Day happens before 2035. And the chances it has already happened in secret? Some people I spoke to estimated 15 percent—about the same as you’d get from one spin of the revolver cylinder.

This whole thing that you can rate your confidence 1-100, chant "Bayes," and it becomes a probability is endlessly frustrating. Sigma-additivity, shmiga-additivity!