I don’t know who would win because the cartels are way better funded, equiped and trained; but they are way less psychotic and bloodthirsty than the yanks
In any case, nobody wants their employees fighting each other so HR is gonna cool down the situation
The cartels would get absolutely smashed doing anything in the open and just move further underground. The only difference is now they’d probably be more likely to use things like roadside bombs. Depending on how things go they could sanitize their image as freedom fighters instead of narcos. And probably a lot more drug use in the rank and file in the USA military.
There’s a massive tunnel network for miles around the border (I know because I saw it in fast and furious).
But seriously, American troops getting picked off in the desert has been our doctrine for 30 years, it’s just come home.