But only a potential warning sign -- fusion power is always 25 years away, but so is the decay of a Promethium-145 atom.

Right, but we expect that for the promethium atom. If physicists had predicted that a certain radioactive sample would decay in a fixed time, and they kept pushing up the time for when it would happen, and didn't alter their hypotheses at all, I'd be very worried about the state of physics.