What would be the example of an outstanding, reasonably-sized (even quantum computers of the future have finite resources) quantum simulation problem that is intractable today but would unlock some economic potential, if solved?
It's true that there could be neat quantum computing shortcuts that maintain calculation accuracy and that aren't doable on classical computers... but then we could also imagine that some neat Quantum Chemistry trick might make classical computers much better too. (We actually have a bunch of these already but they are approximative: DFT, machine learning, pseudo potentials etc.)