Martin's blog post began by talking indirectly about Canonical abandoning Wayland in favor of Mir for future releases of Ubuntu Linux, Wayland support for KWin has been a primary goal of Martin's for the past two years, it took a while for Wayland 1.0 to have a stable and reliable API/ABI, and then earlier this year plans were talked about the KDE/Qt5/Wayland combination.
Martin made it clear in his posting that their Wayland plans were laid well before Canonical's Mir+Ubuntu announcement. I've been talking about Wayland and KDE/KWin since at least 2011 and more details later that year.
Wayland remains to be part of KDE's long-term strategy and so far it's proving to be good. Martin's Sunday afternoon blog post can be read here.