One thing the article forgot to mention is that while yes, ABI compatibility will be broken, there's also a significant focus on mostly maintaining source compatibility. And not just in the KDE Frameworks, actually; the same is true of the Qt 5 effort. That means porting applications will be a much smaller task than Qt/KDE 3->4 was - build systems will have to be adapted to the new modularization of libraries and the use of some removed, previously deprecated APIs will have to be replaced here and there, but there won't be any major API pattern changes forcing application developers' hands.
The bottom line is that this change ought to be mostly invisible to users. The user-facing parts of the KSC will continue to be developed and released while the reorganization goes on, as will be the applications outside the SC, and when the time comes to port these to the new set of libraries, it'll get done fairly quickly.