Hopefully as we pile on more and more examples of different materials exhibiting superconductivity, we can understand it well enough to find a practical high temperature one.

Though I think we could go a long way with the liquid nitrogen temp superconductors now on the market. It's still going to be a real chore to design around, but it's got to be a lot easier to deal with liquid N2 than liquid He.

It's not far off. Engineers see if it's doable for a given budget, physicists show and analyse that it's possible at all.

Similar to a CS paper showing a new algorithm e.g. sorts with x% less swaps than quicksort, it might not actually lead to a performance increase on real hardware.