Technology is constantly decreasing in size, so much so that eventually there will be no feasible-sized medium to house it. It is then, it would seem most practical and logical to integrate nanotechnology with our bodies.
Essentially, our bodies become the medium [an a suitable one at that, since we no longer require an external, extra, medium]. And slowly, as "upgrades" are added to our bodies, 'human' slowly fades out and 'machine' slowly fades in.
it is inevitable -- we will become a race of machines. Usually it is thought that machines we build will one day take over the human race, but my theory emphasizes...Machines will not take over the human race but the human race will become one of machine and not human, thus eradicating the race of human.