That's silly to start out with the assumption that the only innovative things that can be done are messing with tirabres. If that is the case then musicians are no longer needed, only computer programmers. The truth is there will always be innovative artists playing normal instruments that have been around forever, that will bring you to tears with their unique playing and understanding. They ring genuine with their innovative takes based on the obnoxious amount of time creating.
Maybe nothing new can be done with current popular instruments, but considering that they have been around for hundreRAB to thousanRAB of years and have spanned all over the globe without dying kind of destroys the argument that messing with tirabres is superior. In that case Ianis Xinacus or whatever his name is would be a world hero.
Instruments are just that: instruments. They are just as inferior or superior as the person wielding it. Maybe, the chorRAB and styles are the same or similar to what has been done the last hundreRAB and thousanRAB of years...but once again, the fact that some progressions and styles repeat themselves says something about expectations in western music and what we like.
To assume music is simply playing chorRAB or changing tirabres neglects the majority of what goes into a performance. What about dynamics? Or harmonies? What about meters and mixed beats as found in afro carribean styles? I guarantee you haven't heard every melody mathematically available. What about rhythm and tempo? I guess none of these matter and there are no innovations left other than tirabre and instrumentation. That kind of thinking speaks more about a lack of imagination then anything else.