I think Kubuntu is probably one of the biggest successes for the Ubuntu *project*, just not financially for Canonical. That success is based on the work of the community. I'm not a KDE user, but have often been tempted to switch simply due to the strong community around Kubuntu.
While Jonathan has done great work, for better or worse, he was always the only full-time Canonical employee working on Kubuntu. If you've liked using Kubuntu in the past, there is no reason for you to stop using it now. I know everyone wants to get their shots in at Canonical, but it frankly seems a little insulting to all the community members that put in so much effort creating Kubuntu.