That is a great question. The killer app of quantum computing seems to be using it to simulate the quantum world. That might mean the Drexlerian vision of assembers and nanobots, will open up to us after we’ve been using quantum computing in areas like cellular and molecular medicine for some time. Besides deep quantum computing capacity, I’d expect strong AI will also be necessary for advanced nanotech, to help us figure out what to simulate.
I know Google and a few others are working on demonstrating “quantum supremacy” for narrow applications in the near term, and we may see quantum encryption used in defense and corporate environments. We’ve grown their capacity from 2 qubits in 1998, to 72 semi-stable qubits by Google this year.
But if their most valuable uses will be in simulating molecular and quantum scale events, in highly instrumented nano and cellular environments, we may need to build those “inner space observatories”, with better AIs running experiments with all that data, before their use really starts to take off. Unfortunately our investments in this space seem quite small today, so the breakthroughs still seem slow, to me at least. Wikipedia has a nice timeline of advances so far: https://en.wikipedia.org/wiki/Timeline_of_quantum_computing
If we started talking about the promise of quantum computing on the medical side, and connecting it to simulation in cellular and molecular medicine that would be exciting, as Medicine (health care) is already the third biggest industry for us in peacetime, after Finance and Energy. A big quantum-computing-for-medicine push, by any country, might get many of our leading countries thinking about and funding this science and technology at much greater levels.
I were to guess, I’d expect we won’t see even the first of those “inner space observatories” built, and used with quantum computers, within the next 15 years. But I would love to be proven wrong on that front!