I think if ITER works it will be a similar watershed moment for a lot of people. The implications would be significant.

But I don't think there can be any technological achievement which resonants with millennia of human wonderings quite like the moon landing did. That was something you could explain to a Roman and they'd understand the significance of.

If I could postulate anything without feasibility being important I'd say a step change in human life spans. Something like "immortality" say another healthy hundred years arriving all at once.