Heck, Windows looks more like OS X nowadays. And even in the mid-90s, Linux desktops wanted to look like Nextstep, so the Mac envy seems a logical succession (let's better forget the CDE phase).
But the whole design space is really, really small. You're mostly making a distinction by a subtly different look and some procedural differences. This is true for every desktop since the 80s, whether it's System 6, OS X, RISC OS, KDE, GNOME or WPS.
That is what the audience wants. The amount of developers isn't that influential anymore, and even they are most likely to use Windows 95/Nextstep style interfaces since they started out using computers. The old Unix greybeards (and their spiritual successors) populate a very small island with weird palm tress.
There still are about as many, if not more people who use their DE as a glorified terminal multiplexer (or Emacs life support). But for them, "Linux on the Desktop" never was an issue in the first place.
I seriously doubt that anything really new will come on the desktop. Everything that tried failed (mostly integrated systems like Oberon, Smalltalk, Plan 9) for the "common user", or got integrated in the normal desktop (web apps, terminal emulators). Everything new seems to happen on different devices (mostly mobile), and even there I don't see a different frontier, it's mostly a mash-up of traditional desktop GUIs and web apps, adjusted for the limitations on the devices.