True if humans considered themselves as machines if only as organic ones but they don’t hence the distinction inherent in the OP Will machines completely replace all human beings? Per it, humans do not regard themselves as machines believing it more probable to have been created by some divine entity instead of the extremely impersonal forces of nature having slowly assembled us replete with a multitude of malfunctioning subroutines.
The machines invented by humans are not humans, even in the case when it is tried to interpret the machines into the humans or the humans into the machines.
The difference between human and machine will narrow via preduction to an apprehensive phenomenological transversal, making the difference between them neglichable. As more transcription will overcome these differences, they will need not become even noticeable until the primal human connection becomes critically deficient.
This will be the minimal alogarhytm that the whole sequence can be proposed to operate under.
At this minimum over ride, the difference should and will become as an over ride system.
The ethical utilization will prefincturalily become a scripted absolute. Violation will override the automatic systems, so that the order of sequencing will obey the pre ordinal sequencing.
The cybernetic ethical principles will need to build that into the system by default.
I think humans are genetically designed to primarily defend themselves. They cooperate with others as a part of that strategy. They have no inspiration to cooperate unless they see their personal need.
Do you really want machines designed the same way? That is what it would take to make the machines simulacrum of humans.
Currently the effort is to make humans more genetically cooperative to their own sacrifice - to be the simulacrum of machines.
I could envision a combination of both efforts - anything to please and serve the overlords (who eventually get replaced as well).
But what is the real purpose in humanity manufacturing it’s own replacement? Who does that serve?
That is one of the most important question in this issue: Whom does it serve? „Cui bono?“, as the Chinese says. 
The overlords believe that they are being served by this, because they know that they are being served for economic reasons (bubbles everywhere) and ecological reasons (energy problems, soon everywhere too). They want energy saving machines and energy saving humans. Both are to draw their energy mostly from outside the planet earth, in order to preserve it - allegedly. For this more alleged reason and because of their delusion (Godwannabe ) they want humans (inventors) and machines (inventions) to merge. This is rational, yes, but in the end it serves no man, no machine, no machine-man, no man-machine, unless „rationality“ is understood to mean „purely economic benefit“, which would be wrong, and this is not only about economy but also about ecology, more precisely about the consideration for the environment, and that does not mean „benefit“, but „servanthood“, „sacrifice“, „death“.
This whole thing will probably turn out to be a milkmaid’s calculation in the end. 
It could have worked, if the waiver had been made early enough. Waiver also has to do with rationality!
The biggest problem is the desire for power, which here extends to the Godwannabe.
Partially true.
The Enlightenment>
the political>economic>industrial revolutions leading to Malthus predictctions>decolonizaton>
Lead to the rise of the barons of manufacture> making the elite control unavoidable
Marx was an aberration meant to occur.
Merely “partially true”?
Although —
If James was right (and I strongly suspect he was) the idea and name “human” meant “hue-of-Man” - the lower order creatures that made up the higher Man-ager of the paradise Eden originally called “ADM”, “Adam”, “Ahdam”.
So I can see the possible day when those machines, in whatever form, are the actual lower order creature making up the Man(ager) of Earth. And at that point, homosapians will no longer be “humans” - the androids will be instead - just like conservatives in the US are no longer citizens with equal rights, but “domestic terrorists” - the Jews would call them “the goyim” and the Musslims would call them “the kafir” or “infidels” - not humans.
It is an issue of who or what makes up the constituency of who or what is managing/governing life on Earth. 
Fortunately James also had the ethical solution for all of this but it isn’t clear that Man will ever realize it. 
_
Will machines completely replace all human beings?
It’s not so much that machines will fully replace all humans, but that humans will be living in a fully automated world.
Then the next epoch, era, age, kulpa of humanity will begin, of which the already more-automated parts of the world are approaching.
“Hue-of-Man”? And the machines will become this “hue-of-Man”? Will there still be homosapiens then? The homsapiens will then have been replaced, i.e. will have disappeared, right?
But it may also be questionable whether people will still be alive in this “fully automated world”.
I am not saying that people will not be alive then, but only asking whether they will be alive then or not.
What would be the point in automating the world if there is no-one left to utilise and benefit from it? though there may be less humans around by then, and we’ll have a more leisurely/less stressful life and existence, thanks to a much more automated world… for those that will be around to benefit from this shift of the burden of manual labour, from man and beast, to machine.
It could very well be that by that tome, the higher man will becoming the higher consciousness, where man will do away with it’s temporally manifested vorporial substance, and pure consciousness will be all that’s required
Immortality en mass for those who stick to believe in Theism !
Figure that.
*if fear doesn’t destroy us by then
The machines and the androids (both are not humans) will utilise and benefit from a fully automated world. Machines will get what they will need from other machines and vice versa.
Yea, it would not be my world, it would not be your world, and it would not be a world for humans at all, because humans would already be dead then. 
Weird how as life gets less physically/mentally taxing, people seem more miserable, and there’s way more mentally ill folks. What happened to “hard work builds character?”
Thesis.
The people will slowly die out, namely on the following way: They will become demented (their memory is already reduced by censorship). They will have no more memory, i.e. history and history narrations will be no more possible, because the memory for it is missing. They will become communistic, whatever that may mean in reality, because they will be machinized at the same time, become cyborgs. They will be fought and defeated by the androids and the pure machines, so that at the end of this fight no human will be left.
Note and take into account that this is a thesis.
Are you assuming that machines will appreciate this benefitting, or that it will be a passive/non-sentient machine code level operation?
How all very West World…
You seem to think you know exactly what it is that has caused this misery and mental illness in folk.
Is it hard work that builds character, or just work in general? I guess it’s down to what you define hard work as… are you talking working down the mines or long hours at the office, here?
More the latter, Mags. However, the former is also possible, but not yet thinkable for most of us.
The whole world has become a West World, at least in a technical and economical sense. Like it or not. 