I think that could be nice adding an USE flag (like "noslot", for example) for being able to compile KDE with --prefix=/usr, without SLOTs, like gnome and xfce are compiled. The attatched eclasses add the USE flag and a tiny modification. Thanks a lot :-)
Created attachment 104123 [details] kde.eclass
Created attachment 104124 [details] kde-functions.eclass
This is NOT going to happen, is messes with portage workings in a very bad way. If KDE will be unslotted, it will be unslotted completely (KDE4 maybe).