Commercial drivers are the motivators for the development of technologies to a highly mature state, where wealth creation is possible. Development of less mature technologies is dependent on funding from governments, private individuals and other sources. More mature technologies are developed by commercial companies when there is a clear risk-free route to market and the size of the market is well understood.
The largest market by far is likely to be that for medical applications, but this is the one which is the least developed and researched.
The second largest market would be that of security screening, this has been well researched, but emerging products need to be refined and new methods developed to reap the full benefits of this band.
All-weather sensing technology would be a smaller niche market, but one that could give impetus to the other fields when emergent products appear.
The impact of quantum technology is still pretty much of an unknown, but a quantum computer running at clock rates of tens of GHz with the same number of qubits as classical gates in today's computers would change the world beyond all recognition.