Monumental proof settles geometric Langlands conjecture

I'm curious what applications there might be if any in number theory. If I recall, langlands had motivations from string theory concepts which ultimately wasn't as successful as hoped in physics.

String theory is still the only self consistent theory of quantum physics.... I'd say that's extremely successful.

Not particularly, it's so open ended it describes an enormous landscape of possible universes and lacks any specific testable predictions for our universe.

Unless it's been firmed up a great deal in recent times.