Perhaps a group could make a Linux distro with the goal of forking, and Plan9ifying, the source of every package they ship. No one would have to use the resulting distro (other than to demo the neat way that the Plan9ified packages integrate so easily with one another) but the original authors/maintainers of the upstream packages could adopt the Plan9ification patches a la carte, gradually increasing Plan9ification across the board. The patches of one package would always be guaranteed to work with the patches from any other, as the resulting combination has to hang together in the demo distro—and, since this would only be an eventual goal of the group, they would also have to make sure that all their patches didn't expect any Plan9ification on any other package's part.