You're still not answering the hard questions that make this a non-starter.
You're overloading me with hyperbole.
"The blinding white of iOS" -your opinion. I don't have a problem with it.
"There is a lot of demand" -again, your opinion. Based on what? A handful of the same people repeating themselves on forums? You shouldn't take that as any indication of anything. It's nothing. iOS 10 will be on hundreds of millions of devices. Let's just agree that you know positively nothing about the hypothetical demand for such a thing.
"There are already inklings of it in the iOS 10 beta" -there were inklings of it in iOS 9 and iOS 8 too. The fact that Apple has toyed with the possibility of darker themes for some of their Apps is not indicative of anything.
Apple is fully aware of the problems that I've listed before, and I'm sorry to tell you, they preclude the possibility of this becoming a thing. You must also be aware that Apple has an Accessibility feature, which inverts the colors of the entire display, which is effectively dark mode (since iOS is generally light). Most people don't consider this to be what they are looking for, even though it is the only way in which such a thing could ever be done globally.
No hyperbole here, the white IS blinding at night or in the dark, in particular when the phone is first turned on and my eyes are not used to the brightness. It's also VERY bright in complete darkness, such as when I'm in bed and my wife is trying to sleep, let me tell her that's hyperbole. Try using the phone in the dark, a club, concert, movie, etc., yeah not happening. I also believe there is a lot of demand, but that's just my opinion from seeing so much written about it, having at least 2 or more jailbreak apps devoted to it, thousands of google search results, etc., but yes my opinion (because it's a forum, that's why). But I'm sure Apple does their homework and conducts market studies and such, probably the reason they ARE experimenting with a dark theme. Based on that let's just agree that you know positively nothing about the hypothetical demand for such a thing. (Or do you know for a fact that there is no demand for a dark theme? Ahh thought not).
Since you like sources, how are you certain that "they preclude the possibility of this becoming a thing"? Has Apple officially announced there will never be a dark mode? If they did I must have missed it. I'm well aware of the accessibility feature, it's awful. You keep crying about some of us saying that Apple has the ingenuity to make this work, yet Apple surprises us every year with its ingenuity, it would suck if they thought like you. Certainly Microsoft, Google, Samsung, etc don't think like that and all present viable dark themes/modes.
No one knows if Apple will ever produce a dark mode, but it's a certainty they are experimenting with it. To say it will never happen is very short sighted. It *may* never happen, but that's not definite, or 100% as you like.