Note that the readiness problem means that Upstart currently doesn't really work as intended for many server daemons. It's a known problem that has gone unadressed for a long time.
Regarding Debian: following the discussion on debian-devel, no decision has been made regarding what's installed as default, but systemd is supported and it seems to me that it just has the most momentum, both inside and outside Debian. Extrapolating that I think the most likely outcome is that systemd one day ends up being the standard, with a wrapper to generate init scripts for Hurd and FreeBSD kernels, unless someone steps up and implements systemd on those systems.
Regarding launchd: the systemd developer addressed that and you can also find some comparisons online with Google. It just doesn't address a lot of the issues that systemd addresses, and it's probably unlikely Apple would like to take a lot of patches addressing problems that are specific to Linux distributions.
I'm an old school Debian guy, who has switched to Ubuntu simply because they know how to create sane default configs. I'm pro freedesktop.org, it seems life has improved since they have become more standard. In that respect, I really hope Ubuntu goes Systemd ASAP. Upstart was the best option before SystemD existed, but it feels like NIH at this point.
LaunchD is actually the best software, if comparing between the mentioned options. The reason it's not used is because it would require significant porting for GNU/Linux. A great project for some serious programmers, but regardless I hope we get a top tier solution soon.
BTW, a couple responses.
1. To the Traditional BSD Init guy...., Your 100% wrong to consider BSD Init now, and to make it more clear... You would have been wrong 10 years ago. I don't even want it on my embedded systems! I understand KISS, although I think people pervert "KISS" to mean any damn thing they want. I would strive for lightweight, and efficient, software. So while BSD Init is by definition 'simple' and lightweight.. It's not remotely efficient.
2. As for Ubuntu focusing on "bigger issues"... Please tell me when have they ever done such a thing? Bigger as in flashy GUIs? Bigger as in thicker dependencies? Bigger as in rewriting strong 'C' software in Python? That's the only bigger from Ubuntu I know. God forbid they actually put in what the other guys contribute, and when I say 'put in' I mean the BIGGER issues. Our well documented shortcomings, at the System level, and this criticism comes from a Debian/Ubuntu user. what they do right is the "small" issues, like configs, package, and documentation.