Two other options though:
(i) states will realise that a global competition in human enhancement is collectively irrational, and proscribe it through a robust international convention, e.g. as they have with chemical weapons, and nuclear weapons through the non-proliferation treaty
(ii) states will sanction, pressure - and even attack - those who launch mass human enhancement programmes, e.g. as they sometimes do with countries breaking out of the non-proliferation regime