Yes, nothing is inevitable, if people make specific decisions. What do you think is the probability that all people will decide to ignore the ability to go beyond what the vagaries of cosmic rays (mutation, evolution) have left us with? What is the probability that, if you come back to this planet 100 years from now, and look at a mature human species, you will see the same, unaltered hominid architecture, with its susceptibility to cancer, lower back pain, degenerative disease, and an aging process that caps the amount of wisdom and compassion we can develop to a mere 8 decades? Whatever I may want or not want is irrelevant. I am saying that the probability of any of that is basically 0. And if you don't like post-humanism, which humans? Should we have stopped at Homo habilis? Post-humanism was obvious when the first replicator had an offspring that wasn't identical to it, because there are no "humans" per se, and the lesson of the paradox of change cannot be ignored.