I have information available to me that indicates that some of the components necessary for manufacture of the new Ektachrome require a significant production lead time - several months in fact.
So if one production run runs out, and they didn't order the components for the next run several months previously, it isn't a simple matter of just manufacturing some more. Eastman Kodak is like every other film manufacturer now - they have to do their best to estimate demand carefully, because they cannot afford to stockpile inventory.
I've got 4 four rolls in hand, and I'm trying to use them in a variety of lighting conditions, in order to evaluate and share the response.
By the way, the information I have available to me indicates that in addition to the changes necessitated by the fact that the component suppliers no longer can supply exactly the same components as before the discontinuation, Eastman Kodak did make subtle improvements to the film around the areas of acutance and, most important in the current marketplace, stability in the face of adverse storage and shipping conditions.