Wayland is both late and early.
Late in the sense that OS X has had Quartz from the beginning, and Vista started the move to DWM; meanwhile the Linux community was patting itself on the back because Compiz looked cooler than either of those, and didn't see past the surface. X11 is not only an outdated design, it's also a security nightmare.
Early because it's still a mixed bag, and kinda suffers from second system. It's a protocol rather than a library - while it's simpler than X11, it relies heavily on optional extensions for things such as screen capture or even "server" side decorations. Under X11, you could write a spartan-but-functional WM in a 100 lines of C. Under Wayland, a functional compositor needs roughly 50k lines; wlroots can handle most of that, but neither KDE or Gnome uses it, so effectively there's three parallel worlds, with varying level of support for different extensions. Early on, IMHO too much effort went into Weston (the "reference" implementation nobody cares about), and too little into building something like wlroots. It may take a while for the situation to settle.