Ah yes, of course. Sorry, I wasn't thinking clearly, just had the usual UI loop and regular interaction with a computer in mind, you are 100% right, audio should have a very high priority. Nothing more annoying than dropouts. Incidentally, the way most OSs deal with that is by having very large audio buffers which in turn will give you terrible latency. On a hard real time OS you could reduce the size of those buffers quite a bit because you can guarantee they are filled (and emptied) regularly.
This is not straightforwardly true. Using small buffers and real-time scheduling works, but it gives terrible power efficiency on a modern high-performance CPU. What you actually want is a scheme with large buffers that can throw out those buffers if something requiring low latency happens.
A lot of usecases require the audio to be low latency all the time. And I don't just mean professional recording studios or musicians, super mainstream things like gaming (especially VR) are way more immersive with low latency audio.
And video conferencing also gets a lot easier, echo cancellation is so hard when you have a lot of data in flight because you will have to do auto correlation on a much larger amount of data.
I might add audio to this list.