This should not have been happened. Maybe you dis something in a wrong way?
I treid myself and it did not deinstall kde. It is important, not to do any upgrade while the entry for sid is in sources.list. Just install both packages (as told in the wiki), then after this install remove the sid entry at once and repeat an apt update again (this will delte all entries from the sid repo). This step is really important! So you will only get both packages and its dependencies, nothing more. It also will not deinstall kde, if doing so. I suppose, you might have forgotten to do an apt update after installing the two packages, so it looks for me, and of course, then it will deinstall packages with missing dependencies. Solution? Hmm, make sure, the sid entry is removed from sources.list. Then do an apt-get update and apt-get install --reinstall task-kde-desktop (or with your language i.e. task-german-kde-desktop). This should reinstall all necessary packages again. So note: If you do an apt-get update, aptitude update or apt update, you can retrieve to the package list of only packages of the repo, which are active in sources.list. Any of the above commands will set actualise the package lists. Hope, this helps. Best Hans > at least KDE, and now it won't enter run level 5. I added > nouveau.modeset=0 to the "linux" line in grub.cfg, but it's still > running the nouveau driver, or at least that's what inxi -G reports: >