Mavericks is getting rid of skeumorphic design in it's native apps, but for the most part still looks very much like Mountain Lion. I don't expect any major graphical rehaul in OS X for a while, since graphically not much changes between the Developer Previews and the Gold Master in my experience, not to mention the naming transition from cats to places in California should have also been an opportune time to have a graphical rehaul, if they want to have one.