I’m more curious about this from a consumer angle - anything with at least a downstream consumer impact that is exciting? And even if no consumer impact for the foreseeable future, is there anything “cool” or more tangible than massive encryption breaking?
The ______ years question is everyone's best guess. X, Y, and Z though are quantum simulations. Drug discovery, superconductors, "better" alloys (use-case dependent), .... It's shockingly expensive to simulate a properly quantum system, and that cost increases exponentially in its size. 1 atom is manageable usually, ignoring relativity. 2 is an interesting research problem. 3 are tractable if they're homogenous and you're patient. Everything beyond that requires huge simplifications or clever insights (or both). Quantum computing linearizes that simulation cost, for any problem small enough to fit inside the given qubit bounds.
One way to estimate the effect might be to look at current chemistry-related AI/ML news. It's a noiser version of the same results. If that winds up being useful then quantum computers will be even more useful (but perhaps not worth it). If that doesn't advance materials research enough then it's less obvious that a quantum computer will be helpful. Maybe, maybe not.
That may well take multiple lifetimes, greatly reducing its impact. Mere increases in computing power will not break 256 bit Elliptic Curve cryptography for centuries. That will require algorithmic breakthroughs or large scale quantum computers as well.