It really depends upon how we define "unification" itself. Merging the machine with the human in a physical way is already a reality, although we are constantly trying to find better, and more seamless ways to do so. However, if we look broadly at the history of the whole "cyborg" idea, I think that it actually reflects a more mythic structure. Early versions of the cyborg reflect the cultural and philosophical assumptions of what "human" was at the time, meaning that volition remained intact, and that any technological supplements were augmentations or replacements to the original parts of the body.* I think that, culturally, the high point of this idea came in the 1974-1978 TV series, The Six Million Dollar Man (based upon the 1972 Martin Caidin novel, Cyborg), and its 1976-78 spin-off, The Bionic Woman. In each, the bionic implants were completely undetectable with the naked eye, and seamlessly integrated into the bodies of Steve Austin and Jamie Summers. Other versions of enhanced humanity, however, show a growing awareness of the power of computers via Michael Crichton's 1972 novel, The Terminal Man, in which prosthetic neural enhancements bring out a latent psychosis in the novel's main character, Harry Benson . If we look at this collective hyper-mythos holistically, I have a feeling that it would follow a similar pattern/spread of the development of more ancient myths, where the human/god (or human/angel, or human/alien) hybrids are sometimes superhuman and heroic, other times evil and monstrous.
The monstrous ones, however, tend to share similar characteristics, and I think that most prominent is the fact that in those representations, the enhancements seem to mess with the will. On the spectrum of cyborgs here, we're talking about the "Cybermen" of Doctor Who (who made their first appearance in 1966) and the infamous "Borg" who first appeared in Star Trek: The Next Generation in 1989. In varying degrees, each has a hive mentality, a suppression or removal of emotion, and are "integrated" into the collective in violent, invasive, and gruesome ways. The Borg from Star Trek and the Cybermen from the modern Doctor Who era represent that dark side of unification with a technological other. The joining of machine to human is not seamless. Even with the sleek armor of the contemporary iterations of the Cybermen, it's made clear that the "upgrade" process is painful, bloody, and terrifying, and that it's best that what's left of the human inside remains unseen. As for the Borg, the "assimilation" process is initially violent but less explicitly invasive (at least from Star Trek: First Contact), it seems to be more of an injection of nanotechnology that converts a person from inside-out, making them more compatible with the external additions to the body. Regardless of how it's done, the cyborg that remains is cold, unemotional, and relentlessly logical.
So what's the moral of the cyborg fairy tale? And what does it have to do with suffering? Technology is good, and the use of it is something we should do, as long as we are using it and not the other way around (since in each its always a human use of technology itself which beats the cyborgs). When the technology overshadows our humanity, then we're in for trouble. And if we're really not careful, it threatens us on an what I believe to be a very human instinctual level: that of the will. As per my the final entry of my last blog series, the instinct to keep the concept of the will intact evolves with the intellectual capacity of the human species itself. The cyborg mythology grows out of a warning that if the will is tampered with (giving up one's will to the collective), then humanity is lost.
The most important aspect of cyborg mythologies are that the few cyborgs for whom we show pathos are the ones who have come to realize that they are cyborgs and are cognizant that they have lost an aspect of their humanity. In the 2006 Doctor Who arc, "Rise of the Cybermen/The Age of Steel," the Doctor reveals that Cybermen can feel pain (both physical and emotional), but that the pain is artificially suppressed. He defeats them by sending a signal that deactivates that ability, eventually causing all the Cybermen to collapse into what can only be called screaming heaps of existential crises as they recognize that they have been violated and transformed. They feel the physical and psychological pain that their cyborg existence entails. In various Star Trek TV shows and films, we gain many insights into the Borg collective via characters who are separated from the hive, and begin to regain their human characteristics -- most notably, the ability to choose for themselves, and even name themselves (i.e. "Hugh," from the Star Trek: The Next Generation episode "I, Borg").
I know that there are many, many other examples of this in sci-fi. For the most part and from a mythological standpoint, however, cyborgs are inhuman when they do not have an awareness of their suffering. They are either defeated or "re-humanized" not just by separating them from the collective, but by making them aware that as a part of the collective, they were actually suffering, but couldn't realize it. Especially in the Star Trek mythos, newly separated Borg describe missing the sounds of the thoughts of others; and must now deal with feeling vulnerable, ineffective, and most importantly to the mythos -- alone. This realization then vindicates and legitimizes our human suffering. The moral of the story is that we all feel alone and vulnerable. That's what makes us human. We should embrace this existential angst, privilege it, and even worship and venerate it.
If Nietzsche were alive today, I believe he would see an amorphous "technology" as the bastard stepchild of the union of the institutions of science and religion. Technology would be yet another mythical iteration of our Apollonian desire to structure and order that which we do not know or understand. I would take this a step further, however. AIs, cyborgs, singularities, are narratives, and are products of our human survival instinct: to protect the self-aware, self-reflexive, thinking self -- and all of the 'flaws' that characterize it.
Like any religion, then, anything with this techno-mythic flavor will have its adherents and its detractors. The more popular and accepted human enhancements become, the more entrenched will anti-technology/enhancement groups will become. Any major leaps in either human enhancement or AI developments will create proportionately passionate anti-technology fanaticism. The inevitability of these developments, however, is clear: not because some 'rule' of technological progression exists; but because suffering exists. The byproduct of our advanced cognition and its ability to create a self/other dichotomy (which itself is the basis of representational thought) is an ability to objectify ourselves. As long as we can do that, we will always be able to see ourselves as individual entities. Knowing oneself as an entity is contingent upon knowing that which is not oneself. To be cognizant of an other then necessitates an awareness of the space between the knower and what is known. And in that space is absence.
Absence will always hold the promise (or the hope) of connection. Thus, humanity will always create something in that absence to which it can connect, whether that object is something made in the phenomenal world, or an imagined idea or presence within it. simply through our ability to think representationally, and without any type of technological singularity or enhancement, we transcend ourselves every day.
And if our myths are any indication, transcendence is a lonely business.
* See Edgar Allan Poe's short story from 1843, "The Man That was Used Up." French Writer's Jean de la Hire's 1908 character, "Nyctalope," was also a cyborg, and appeared in the novel L'Homme Qui Peut Vivre Dans L'eau (The Man Who can Live in Water)