Excalibur has been used in Neptune for several years now but with the latest Kickoff development in upstream KDE Plasma its not necessary to maintain this menu any longer as the kickoff menu mostly adapts the design layout and ideas of usage and even improve upon.
So I hereby announce the retirement of Excalibur and from this date on the default neptune look has been updated to reflect that change. So don't be confused if a new artwork update package brings also the new default menu with it. It won't affect existing systems immediately but only if you change your Desktop Theme and choose to take over the embeded Plasma layout.