Earlier quoted context omitted.
Even if they do, the cartels already own huge man & firepower. They will just move on to the next thing, maybe coffee, avocados, oil whatever. When you have accumulated so much power you can demand cash from the world around you.
They'll probably move onto mass producing weaponry, which, depending on the sophistication and scale, could be big issues for the rest of the world. They already partner with terrorist groups and other unsavory orgs as-is. Any group worth mentioning these days interfaces with the cartels
I think controlling municipalities like they are is working fine for them. No need to mass produce weapons when you can just buy them.