ralul, calm down - 10% of the transition are done - there will be a few breaks, but there is an easy solution: Don't touch a running system or have a good and tested rollback or recovery strategy.
Yes, don't touch your Debian yet if your working environment works ... My working horse at the moment is Gentoo using an older gcc-4.9 toolchain. Thus I can experiment with my Debian Sid partition: I ever wanted to give Gnome-3.16 a second try after years.
I purged all of Kde, sddm, vlc, kaffeine, xfce. I disabled siduction kdenext repos and only kept the Debian Sid unstable package list. Gnome installed and runs well (I don't know if Gnome had to transit at all, has it C++ code?). All of my remaining Debian Sid packages went through a full dist-upgrade including libreoffice-5 (this one pulls in a newer boost-dateime). Afterwards I was able to reinstall
- sddm, which pulled a lot of kde and plasma in again
- vlc and kaffeine,
where I had to purge some of multimedia libs in case there was a newer one with an ending name 'v5'
Debian Sid is usable riding Gnome-3.16 as Desktop.