What we need, are farm-raised elephants. Then the world would have a steady supply of responsibly harvested "agricultural ivory", and the demand for "free range ivory" would diminish. The wild elephant population would be less threatened by poaching and could go back to worrying about habitat destruction.
Seriously though, I expect the US ban on ivory trade will prove about as effective as the "war on drugs".
Also, the OP's claim that the ivory ban sets precedent for an exotic wood ban has some merit. Remember that federal marshals raided Gibson Guitars for importing ebony. The Lacey Act could easily be expanded to criminalize sales and transfer of pens (as well as guitars) made from legally acquired wood.
I'm afraid I've overstepped the bounds on political discussion, but woodworkers should legitimately be concerned about preserving the medium of their craft, and of others' crafts. Pastor Martin Niemöller's famous quotation seems applicable here.
Regards,
Eric