GEGL integration

It will eventually, When fully impemented it should allow several forms of non-destructive editing. Filtering layers will be one of them. Another should be the ability to selectly undo abritrary steps without having to go through the undo-undo-undo song and dance... that is if you don't like a edit you made 12 steps ago you don't have to undo 12 steps.. you can go and undo that portion of history without losing the work you've done since then.

That sort of thing should improve the workflow massively and increase the speed at which it makes it possible to get things done. But that sort of thing is not going to make it into 2.8