Panda,
The site that is the source data for your post is this;
http://www.bestplaces.net/city/Irvine-California.aspx
The key sentence in the site when talking about those stats is this;
"The unemployment rate in Irvine is 5.90 percent(U.S. avg. is 8.50%). Recent job growth is...
Wasn't the land being used for Montecito and Carmel originally intended for a middle school? Would they ever use this unplanned space for a middle school? I would think if you add another 680 housing units the demand might come in line for another school.