Wayland tries to be a simpler and smaller system than X11. For it to specify equivalents to ICCCM and EWMH would be way beyond its scope. But there's nothing preventing such equivalents from being standardized; it just won't be part of Wayland, since Wayland also wants to target use cases where such things would be inapplicable. If there ends up being a proliferation of wayland implementations that support pluggable components, I think we'll definitely see some quick standardization of the necessary interfaces. But at the moment people are still working on successfully using one desktop environment at a time, so good support for the mashups will have to wait.