People mostly seem to like KDE Plasma more than GNOME, but Ubuntu still seems way more popular. Will Kubuntu ever overtake Ubuntu? Will people ever default to saying Kubuntu instead of saying Ubuntu even when speaking generally about *buntus?
Same questions for other distros like Fedora/Fedora KDE


Simply no. Canonical always used GNOME and I don’t see that’s changing.
From the user’s point of view, if you discovered KDE you might have discover other distros as well. Kubuntu still be your start point though, or even where you settle.
Ubuntu used to have it’s own GTK based desktop, Unity, from 11.04 to 17.04.
Eh, a small gap in the CV doesn’t change that I guess. :)
Also IIRC Unity started with 10.10, as a netbook edition.
Yes, but later it became the standard DE. The original Unity was a great DE for Netbooks.
Indeed it was. I still miss the last Gnome 2 version with 2.32 though (I think).
except during the period when they used https://en.wikipedia.org/wiki/Unity_(user_interface)
Well, they try things time to time. They had their own init system, own display server. They eventually went with more mainstream variants, almost every time.