If it is ready why not release it without the PBR? PMDG as an example just did an update on the 747 to convert to PBR, could you not do the same when you finally finish the PBR textures?
Nobody ever said it's "ready", not even with non-PBR textures. There's nothing to convert, the scenery was made as a PBR project even before PBR support for P3D was announced, it's just the scenery is incredibly big, and it's constantly changing AS WE SPEAK.
We already remade some parts of the ground, because we got some pictures which shows even the current AIRAC chart included in the latest Navigraph update, it's already obsolete, and I expect it will change again, many times, before it will be released.