Apple didn’t start any dark mode trend. They’ve actually been on the trailing edge in such matters, rather than the leading edge. There’s been a repeating cycle of rigidity, followed by flexible theming support, then back to rigidity by way of allowing apps to control things, then introducing a new kind of theming support (always weaker than the last iteration); and each time you introduce the new hotness, it’s touted as a groundbreaking revolution, completely ignoring the fact that ten and twenty years ago the system probably had the same functionality. Windows has gone through a couple of iterations of this loop; Android has as well; macOS has too, though it was never as strong as Windows’; Windows Phone was always dark; iOS never really gave the flexibility before last year. In the current cycle, Windows and Android both had it for more than a year before Apple.

I think the dark mode theming capacity will probably be more permanent this time through, but it could still fizzle out within ten years.

Of course, nobody seems to remember Android 4's design language, Holo, had a light and a dark theme. For the exact same reason too: the Nexus phones were pioneering OLED displays.