> We're are still at least tens of years away when there even could be enough cubits to brake SHA-256 and way before we'll just update the algorithm
You have no idea. We could be 5 years away. Nobody can know what quantum breakthroughs will or will not happen. (That's true for AI also, which can support the error-correction side). The nature of unexpected research breakthroughs is that they are *unexpected*, and "It'll never happen in such and such a time" is not a very strong argument.
Also to have any upgrade propagate widely enough to save bitcoin from a massive and potentially life-ending system shock we need at least 10 years of propagation, give how human nature impedes propagation. Maybe by 2035 the network will be hardened enough to survive the shock.
None of those "features" you mentioned help avoid catastrophe by the way. A machine with enough q-bits will bulldoze in with ease.
This is a real thing.
