This reminds me an awful lot of KDE's KParts architecture, which among other things, can allow a large program (such as an IDE) to swap out one editor component

This reminds me an awful lot of KDE's KParts architecture, which among other things, can allow a large program (such as an IDE) to swap out one editor component for another at runtime (many KDE apps do this already, allowing you to switch between Kate and Vim editor components).