Why was nature valley cereal discontinued?

It appears you're mistaken. Nature Valley Cereal is still available for purchase. There is no record of it being discontinued.

You might be thinking of a specific flavor or type of Nature Valley cereal that was discontinued, or perhaps you're thinking of a different brand entirely.

To clarify, could you please:

* Specify which Nature Valley cereal you're referring to? (e.g., Nature Valley Oats 'n Honey, Nature Valley Granola, etc.)

* Provide any further details about why you believe it was discontinued (e.g., where you saw information about it being discontinued).

With more information, I can better understand what you're asking and provide a more helpful response.