[KAMiKAZOW]

Canonical never contributed much to KDE. Yes, a few bits here and there but overall mostly negligible.

Blue Systems OTOH is a big KDE contributor. Things like KDE Search improved a lot thanks to Blue's involvement. As for Kubuntu: It appears to me that mostly the same people are involved with it. The only KDE thing mostly specific to Kubuntu is Muon (and that's being ported to Debian as we speak). Everything else by Blue Systems is AFAIK cross-distro.

The Kubuntu guys already announced that Canonical's own display server Mir is not an option. Therefore it remains to be seen how feasible Kubuntu remains with Canonical pushing a Wayland competitor.