Just a few minor corrections, if you don't mind.
1) Filters don't absolutely have to be become GEGL operations all at once, but it would be nice.
2) OpenEXR and RGBE support is not a possibility, it's a reality by now, albeit in an unreleased state. Also, the OpenEXR plugin is very simplistic and doesn't yet provide any user-configurable settings for opening/exporting.
3) It's OpenCL rather than OpenGL, but the outcome is the same: GPU-side rendering and processing. Multithreading was experimentally added this summer as well.
4) There is no final UI decision made on how non-destructive editing would be implemented, exactly. GIMP might provide direct access to editing the graph or it might not. This is simply undecided, as there are more pressing matters currently.
5) Automating GIMP will eventually become simpler thanks to GEGL indeed, although, with a tree of nodes, there doesn't necessarily have to be a record button