Historically speaking, God has used one nation to punish another nation (e.g. Jdg 6:1). Of course no nation is perfect, but Mexico has historically been a very corrupt nation which is one of the reasons why most of its citizens can't get out of that country fast enough. God may have been using the US to punish Mexico back in 1848 and possibly could do so again.
If the Mexican government cared just one hoot about its people, they would follow the German and Japanese model. You declare war on the US, even fire a shot into the country (being careful not to kill anyone), then immediately unconditionally surrender to the US, letting them take over for about ten years. Within a generation, Mexico would become one of the world's economic superpowers. It might even happen faster since Mexico wouldn't be devastated by an all out war.