The Kubuntu team has a wide degree of freedom in how they structure Kubuntu - which apps they include and how they configure it by default. I doubt they will embrace Unity immediately, unless it proves extremely popular amongst Kubuntu users.
That said, we have done a lot of work to ensure that many key aspects of the interface and API's work across both GNOME and KDE. Menu's, indicators, notifications and lots of other goodness have been built for both GTK and Qt apps and are tested across both Ubuntu and Kubuntu. So Unity should work very nicely as the shell for Kubuntu if you want that yourself or if the Kubuntu folks decide to go that route.