Humans are too attached to their biological bodies, they find it too difficult, to overcome their biological limitations. Only the renunciation of the biological body can give us a chance to grow up to the reason. But it seems like that humans will hardly ever stop being animals. In this case they will be bound to become a thing of the past, giving room to the creatures that are not originally related to organics, and that were initially made by humans as their instruments and tools. It is conscious machines that can make people behave in accord with reason, like modern humans make animals betray their natural inclinations to support human activities. Machines that follow conscious goals will be able to curtail the human savagery, confining it to the carefully controllable reservations (conservancy areas), and possible transforming the human organism in the direction of more consciousness and reason.
Of course, there is a slight hope of a symbiosis of humans and machines, keeping biological bodies as one of the possible carriers of a distributed reason. But this kind of medium is not universal enough, it can only exist in a very limited range of environmental parameters. This is too restrictive for conscious development, which is to assimilate the entire Universe. Conscious machines (with an active employment of nanotechnologies) look more preferable in this respect.
It seems like the existence of Homo sapiens was necessary as an intermediate phase between the animal world and the reason. Through humans, nature creates the forms of matter that could not develop on the biological level. As soon as these forms will become self-contained enough, there will no longer be the need in the humanity, and it will end its days as an historical relict, a protected species that is artificially conserved. No doubt, many people will like changing their organic bodies to a more universal shell, and this will be possible some day. The difference between humans and machines will gradually fade. But there certainly will be some people who would cling to their biological exceptionality and develop in the dead end direction. They will be given this possibility; but history will run away from them to the future.