As long as their is creativity: never. For starters, most music in the world is improvised and is therefore a living, evolving craft.
But when you put a whole lot of arbitrary constraints on the matter, then you start to see what people refer to as "running out" of music.
If you take most contemporary pop styles of music, they are equal tempered, diatonic, largely 4/4 and based around 2^x form arrangements. The same melodic fragment, even if played by 2 separate musicians on 2 separate instruments in different songs, becomes contentious under copyright. With these kinds of constraints, it's no surprise that you'd feel as though nothing new is being made. That coupled with the mass production/"song made in a week" type of approach to commercial music and things look dim.
However, musicians have it better than ever with the advent of computer based DSP. You can construct sound right from the bottom up with component sine waves, filter, distort and shape to your hearts content. You can use whatever time signatures and chronological patterns you want, and different tuning systems are easy too. Then you get into the more conceptual stuff. Is a piece of music set in stone as a recording, or can it be a set of guidelines which a rudimentary program uses to generate a soundscape or piece of music? Or what if something scans your body and gives you a bespoke composition for you?
Really, the possibilities are on the scale of "atoms in the universe". Get back to me once the sun has died, then we will re-evaluate things.