Is a piano inevitable?
l guess its the same with would an organ be inevitable.Modern organs are very popular with musicians as they can replicate so many different sounds including the piano.lt had to happen.A bit like evolution l guess if one believes in evolution.
The essence of evolutionary change must be the chance of new environments opening up in which organisms and sometimes newly evolved organisms can thrive. This does not make any animal or plant inevitable as a distinct genome. Not that you suggested a parallel of nature with the development of the piano but do so would not be fair since the comparison with human cultural artefacts i.e. musical instruments or poetry are not like with like.
Evolution has no evidence of being ‘driven’ but the design of musical instruments does.
The former is random, the latter culturally engineered. Pianos exist because they are or refinement of earlier less tractable instruments. You could then argue that with the tendency towards mankind improving his own world, the clavicembalos of JS Bach would inevitably be supplanted by an improved form, an evolved and better-suited-to-its-purpose form.
As Atomant has noted above; the electronic organ has partially replaced the piano...was that "inevitable"?
Perhaps the intent of the OP was to show the similarity between instrument makers tinkering with different sound generating techniques, and then public acceptance, approval and most important funding having the enterprise flourish, and the process of mutation first, discovering niche later (or variety thereof) evolution scenario. the gist is: --nothing happens in this world without a creative impetus.
BSW there is a big difference to have music generated by a piece of cardboard (a speaker) and the sound of a real Grand.