We use general relativity for anything fast moving I think. Not sure, but pretty sure. GPS wouldn't work with newton. But that's the point, newton mostly works to within an error of measurement
Examples of using GR are few, GPS being the most prominent one, another being astronomy. Making this point, SR would be a better example.
Maybe a better description would be "we use GR to describe extremely precise time measurements, or the movement of extremely large things". The latter has not yet lead to any devices being built, as far as I know.
The "disappointing" scenarios would be either that the engineering task turns out to be so hard that it stays "20 years away" for another century, or that quantum computers get built but nobody can find a really impactful and useful application.
"It turns out that GPS must account for both special relativity and general relativity to deliver position at 1-meter level and time at 100-nanosecond level to its users."