We'll see a full-fledged war along the border (citizens against the insurgents), if Washington doesn't start responding.
Maybe the government in Washington is no longer the one in control in that area. Having abandoned its citizens and abrogated its responsibilities to them, perhaps it's time for the USA to experience a governmental breakup like that the Soviet Union experienced in 1991.
If so, the causis belli certainly exists for those in Texas, New Mexico, Arizona, Colorado and California's border areas. And a few others, as well.