As both industries grow, this is a great move by the NOP to both identify the current organic practices within these industries and lay a potential roadmap for organic certification for produce grown with these methods.
As written in another post, it is unlikely that we will see truly "organic" hydroponic produce anytime soon. That will require high quality synthesis of specific ionic compounds from organic sources. The technology simply isn't there yet, and many of the hydroponic nutrients are still mined from the earth and then processed. There are ways to grow hydroponically with organic methods, but so far no one has achieved it at a commercial scale (that we know about).
That said, hydroponics, especially when grown at scale, is arguably the cleanest method for growing produce. Because there are few organic materials except the plants themselves, the likelihood of harmful bacteria like e-coli or salmonella growing on plant leaves is practically zero. Sounds pretty great, right? With it unlikely that the USDA approves anything but very small-scale hydroponics as organic, we would push hydroponic farmers to start the marketing campaign advocating for the benefits of hydroponics. It will take awhile, but once the word is out, a "hydroponically-grown" label could be just as enticing to the savvy consumer as "organic."