I rather think that we're past our ability to make useful yet comprehensible (to us) models in physics. The only avenue is to make useful and incomprehensible models. Using machine learning for that is one way. String theory might be on the boundary where it's borderline comprehensible (for a few select people), but at the cost of being only borderline useful (maybe).
This could well be the case, though I don't know how one could falsify this without a superhuman intelligence, so is rather unscientific.
I think the less controversial stance is that we're running out of road on what we can test with Earth-bound particle accelerators, and there are still open problems. That's a problem with what we can verify rather than what we can conceive, which could be an impasse to a grand unifying theory.
