"Exciting times" brings to mind the Chinese curse of living in interesting times.

Lost coins on the chain will indeed be vulnerable to QCs as these are the ones that won't be moved to quantum-safe addresses following a bitcoin upgrade. Making these coins available for theft by QCs could be terrible for bitcoin's price, but more so for faith in crypto as a whole, similarly if anything not moved was burned to prevent theft by QCs. There's no easy answer here.