I was wondering... When nuclear fusion becomes a thing in "the next 30 years", i.e., almost infinite and free energy production, what do you think will happen to proof of work? Will make the bitcoin consensus stronger or weaker?
If nuclear fusion is going to be centralized, as it seems for now (look at the ITER), then I think it can be a problem. Nation-state attacks could be feasible.
What made you think that nuclear energy is free!!! It's clean energy but it's not free in any way so get your facts right. But I do agree with your statement about energy production centralization. It may become difficult for big scale miners to continue their mining operations if a government wants to crack down on the mining farms. But that was always a risk because in majority of the countries, government owns the electricity distribution grid and controls the supply. So I don't think governments will take any such drastic step.
But even for argument if this happens, it will give rise to the home based miners. As the big players will be out of the network, the mining difficulty will go down drastically which will become profitable for the small miners to run their mining operations.