What are the chances of California and the Southwest seceding from the USA and rejoining Mexico?

The chances are growing by the day. As soon as the Hispanic population in the border states is in the majority, and that time is not in the too distant future, this may become a real issue. Of course I don't really think the Mexican government would encourage such an event -- it is probably quite content with millions of its citizens living in a foreign country (the U.S.) and having someone else being responsible for their education, health care, and human services.