Mexico.. 'Illegal inhabitants' in California and Arizona would join with Mexicans down south to overtake Southern California and parts of Arizona. Perhaps this was Eric Holder's plan when he sent thousands of assault weapons to Mexican drug cartels.
The big picture boils down to motivation.. I think Texas is best positioned, motivationally to combat ideology foreign to our Constitution. Are we outnumbered? Probably.
I live in San Diego County. And most Mexicans around here are lazy and unarmed. Perhaps those you speak of are different.