We would have to declare the cartels to be enemy terrorists, and military would have to be allowed to go house to house to clean things up. Once peace is established, we could grant non-combatants full citizenship rights (or maybe just those born after peace is established). Not gonna happen, of course (and I'm not lobbying for it, just carelessly speculating about what would be best for the US and those people in the long run). We will just end up in a fight with China, which will be worse.
The biggest problem for American businesses in Mexico is (1) danger to staff, and (2) corrupt legal system. At least China has the safety thing pretty much figured out. And, the "corruption" in China is more just a systemic bias of "China First." Mexico is far worse, in that the judges are in the back pockets of cartels, because their kids will be beheaded.
Or, we just encourage businesses to go to Panama or other more secure nations. Chile is in pretty good shape.