Yes. It's a spectrum. In the worst case, quantum computers only help us gain a deep understanding of quantum physics. In the best case, they beat classical computers on optimizations problems as well. Materials science falls somewhere along this spectrum.

Yes. Though it's more than a one dimensional spectrum:

There's also the orthogonal possibility that quantum computers don't work, or don't work well, and eventually we'll learn some new physics that tells us why. (Given that orthodox quantum mechanics says that quantum computers work, but so far they've been hard to do. It's most likely 'just' engineering issues, but there's still the possibility of something deeper.)