Interesting. Seems to me there should be a good substitute for the ivory pieces. Reminds me of Gibson and Martin getting their guitars and wood stock confiscated due to the rarity of some woods. The ones already made should be grandfathered. There should be no new production of anything using Elephant Ivory. They will be gone from the earth which would be just another sad implication of humanity's impact.
But, it's perfectly okay to defoliate the entire Amazon rain forest as fast as is humanly possible. Hell, we even contribute to that endeavor through loans, trade practices, etc. Go figure.
If the wood isn't sustainable and rare, it should be protected too. I certainly am not in favor of defoliating the forests, anywhere for that matter. I walk the walk...my plinths are steel and aluminum or aluminum and panerholz...a man made/engineered wood so to speak.
It's my understanding that certain woods used in instruments are still an issue. Have papers when one travels.
A substitute is only that usually, not the best
Heck, I remember reading that an oil for certain applications cannot be emulated just right, so only whale oil will do.