Debian's latest round of angry mailing list threads have been about some combination of init systems, future direction and project governance. The details aren't particularly important here, and pretty much everything worthwhile in favour of or against each position has already been said several times, but I think this bit is important enough that it bears repeating: the reason I voted "we didn't need this General Resolution" ahead of the other options is that I hope we can continue to use our normal technical and decision-making processes to make Debian 8 the best possible OS distribution for everyone. That includes people who like systemd, people who dislike systemd, people who don't care either way and just want the OS to work, and everyone in between those extremes.
I think that works best when we do things, and least well when a lot of time and energy get diverted into talking about doing things. I've been trying to do my small part of the former by fixing some release-critical bugs so we can release Debian 8. Please join in, and remember to write good unblock requests so our hard-working release team can get through them in a finite time. I realise not everyone will agree with my idea of which bugs, which features and which combinations of packages are highest-priority; that's fine, there are plenty of bugs to go round!
Regarding init systems specifically, Debian 'jessie' currently works with at least systemd-sysv or sysvinit-core as pid 1 (probably also Upstart, but I haven't tried that) and I'm confident that Debian developers won't let either of those regress before it's released as Debian 8.
I expect the freeze for Debian 'stretch' (presumably Debian 9) to be a couple of years away, so it seems premature to say anything about what will or won't be supported there; that depends on what upstream developers do, and what Debian developers do, between now and then. What I can predict is that the components that get useful bug reports, active maintenance, thorough testing, careful review, and similar help from contributors will work better than the things that don't; so if you like a component and want it to be supported in Debian, you can help by, well, supporting it.
PS. If you want the Debian 8 installer to leave you running sysvinit as pid 1 after the first reboot, here's a suitable incantation to add to the kernel command-line in the installer's bootloader. This one certainly worked when KiBi asked for testing a few days ago:
preseed/late_command="in-target apt-get install -y sysvinit-core"
I think that corresponds to this line in a preseeding file, if you use those:
d-i preseed/late_command string in-target apt-get install -y sysvinit-core
A similar apt-get command, without the in-target prefix, should work on an installed system that already has systemd-sysv. Depending on other installed software, you might need to add systemd-shim to the command line too, but when I tried it, apt-get was able to work that out for itself.
If you use aptitude instead of apt-get, double-check what it will do before saying "yes" to this particular switchover: its heuristic for resolving conflicts seems to be rather more trigger-happy about removing packages than the one in apt-get.