We're never going back to the days of pitchers like Roy Halladay, and that was apparent even before the opener became a thing.
If there are pitchers rotting away in the minor leagues because teams are waiting for them to develop into competent starters, I don't mind the idea of bringing them up to be used as an opener if that's how they can provide maximum value. Good on them for getting paid. And at the end of the day, if a pitcher proves themselves capable of being a Sale or Scherzer type workhorse, the opener will literally have zero impact on them as those types are always going to have spots. The opener is really just the death of the mediocre 4th/5th starter.