A few months ago Rood tackled the issue of our favorite breakfast food in his article, "The golden age of cereal." The most fascinating insight from this analysis is that "nearly half of all cereals last less than 5 years before being discontinued." In other words, manufacturers are trying all kinds of recipes and ideas, but most do not succeed. In fact, the pace of new cereals introduced is increasing, illustrated by the fact that "the majority of cereals have been launched in the past ~10 years (over 1/3 of all cereals."
The article is brief, without too many more great discoveries, although his table of cereals and the time that they have been on the market, is a great resource. Rood also offers a few reflections based on this data as to how cereal companies might reverse declining trends.
Check it out. It's a short, interesting read!