The work you might have heard about GEGL - is all about providing foundations for such non-destructive editing. The highlighted split-view / curtain preview in the blog post is implemented using these new capabilities provided by GEGL. Adding new features that cement themselves as new things in the file format is part of GIMPs roadmap after GIMP-2.10 / 3.0. 2.10 / 3.0 are aiming to provide the same functionality that GIMP-2.6 / 2.8 provided but with GEGL as the core and thus higher bitdepth.