It does not matter what Apple does - there is tight controls on the system and code contributed to Darwin might never see life as part of the actual Mac OSX released by Apple.
The init process in Unix and Linux is a very special thing - if it ever crashes, so does the whole machine. It is the first process started by the Kernel after it finishes initializing the system and mounting the root filesystem and is the "parent" of any process that deliberately orphans it's child-processes before exiting itself. It is also in charge of "reaping" any zombie processes. With each addition to its duties the area for an error to happen increases, which increases the risk that the system will just suddenly crash.
This is a problem that people lambasted Microsoft for from the birth of Windows through it's transition to a 32 bit system and still continues to this day for an extent - that they had one piece of the system doing a lot of work and having a wide surface for errors but still critical for everything to work properly. I am loathe to praise Microsoft for anything, but I must praise them for this - they have been moving away from that and I have actually found Windows 7 to be pleasantly stable - to the point of actually being able to recover from the graphics drivers crashing and managing to recover and re-load and re-initialize the system without losing any data. They have turned things around and begun to compartmentalize things to an extremely high degree - lowering the amount of code in each component, raising the ability of their programmers to actively find and fix the bugs during development and lowering the chance that a user will actually hit one of those bugs.
That compartmentalization and modularity (of the userspace, at least) was a hallmark of the design of Unix - each piece did exactly one job and did it well - as well as being as small as possible to reduce the amount of space there was for an error to be in. Yet with this "systemd" we see Lennart Poettering leading the charge to turn that around in order to save some small fraction of time during the boot process. That he created "Pulse Audio" - which appears to have flopped severely and, at least for me, was the cause of a lot of problems (not just for me - I remember finding thousands of people finding that problems were being solved when they got rid of Pulse Audio when I first started having those problems) - seems to be lost on people.
No, one mistake does not make everything someone does wrong, but in this case sacrificing simplicity and modularity so you can "do the boot process faster" is a wonderful idea. Extending the system that does that so it subsumes some of those processes it used to start in parallel for a faster boot time is just idiocy. What's next? Am I going to find that I can send a "draw an ASCII art of a kitchen sink" command to systemd and have it take over the current TTY to do just that?
If systemd was just a system for organizing the boot process, adding some complexity to simplify much more and making sure that daemons providing services get run in parallel to boot the systems boot time... Well, I'd have absolutely no objection to it. Instead it has subsumed separate projects and forced people to fork them or recreate them if they do not want to use systemd. Further, it appears that people that don't like systemd but like Gnome will soon lose the option to run new versions of Gnome because several key components of Gnome now have a hard dependency for systemd or one of it's sub-projects. Open Source is supposed to be about choice and by forcing people to use something that they might not want to that choice is being taken away.
So, with all the sarcasm I can muster, all those systemd supporters out there and it's creator have my hearty applause for doing something that goes against one of the key tenets of the Open Source movement. Bravo! You've successfully taken away something from people that you claim to be supporting. What a show of hypocracy!