Not really. In purely economic terms, even a union with Canada would be a problem. They have natural resources and an educated workforce, but culturally they are more accustomed to government “over-reaching” than we. Mexico has oil, and tequila. That’s about it. Bad idea.
Mexico also has heroin, methamphetamine, cocaine and marijuana.
Mexico has huge tourism potential and lots of land for building homes, retirement homes, businesses, etc. Also there is much potential in fishery and agriculture.
In addition, if American companies had free reign in Mexico they could employ all the potential ‘illegals’ right there ... no need to cross the border to get a low wage job. A Mexican could stay home and get a low wage (factory or service sector) job ... the same exact jobs they have when they move North.