Yes, please... I vote +1 for not silently replace sysvinit by systemd, when upgrading from Debian 7, to 8.
Also, during Debian 8 installation, please, provide an "altinit" option (http://pyro.eu.org/debian/pool/main/d/debian-altinit/
?), so, people can choose between systemd / sysvinit (before 1st boot). I know that it seems easy to just "apt-get install sysvinit-core" after install (1st boot) but, at least, Debian users will have an option to select a well tested, init system, while it is fully supported.
I'm seeing that, when with systemd, people are complaining that it does not always work, so, it seems that, when with systemd, Debian will stop working on a system that it always worked previously. Then, if people don't have a option to select the `sysvinit-core` during the installation, this will be a huge step back... They'll be forced to install Debian 7, then upgrade to Debian 8, on those machines that systemd seems to not work.
Also, the current Populatiry Contest is unfair, because it shows systemd winning, when it is being pushed.
I like the idea of a new init for this century BUT, since systemd developers lack of social skills (read: "Linus already kicked those guys from kernel dev"), it is wise to wait, at least, until ~2019, to replace sysvinit / upstart, by systemd. I'll stick with Debian 8 + sysvinit (or Ubuntu 14.04 with upstart), until ~2019.
I'm not against change, I'm already using IPv6 and NFTables on a daily basis... ;-)
BTW, if the `sysvinit-core` maintainers will maintain it for, lets say, until kFreeBSD dies, so, why not let people choose between the two? Then, we'll have time to see if this "systemd thing" will become a standard, or not. It is safe to keep two options, until systemd guys proves to the open source community, that they deserve more respect.
Also, providing two init systems during Debian 8 cycle (or until kFreeBSD remains around), will calm down people all over the world. People already don't like change (not me), and a pushed change is even worse, it will make them very unhappy / disappointed / betrayed.