It might finally enable weather forecasts to be accurate more than a few days out as well. It will be interesting to know precisely where hurricanes will make landfall, instead of the spaghetti models that we have now which are better than nothing, but still leave a lot to be desired. I think quantum computers will be like GPS in the sense that governments will have the cutting edge capabilities before civilians. You could make unbreakable (with classical computers) and tamper-evident transmissions which will be of interest to militaries. Encryption like we have now with SHA-256 could be compromised, and would destroy coins that use this technology (like Bitcoin) unless some serious changes are implemented. It's all pretty fascinating though, and the connection between mathematics, computer science, and physics is kind of inspiring in a way.