E: Also, I totally just realized the possibility of all this shit pushing mexico's government into actual straight up collusion with the cartels. It would be an amazing sort of fucked up if the civil war we've been largely enabling we also manage to cause to conclude in the favor of the side we really don't like. Pretty sure it's not a very large possibility, but... still.
Economic problems can certainly destabilize a country undergoing economic collapse and the government itself is vulnerable.
If things did happen that way, we'd possibly be, *ahem*, forced, to intervene.
You say that like organized crime hasn't been causing widespread corruption and violence there for the better part of a decade. They're right where they want to be.
scenario: the border manages to cut down smuggling.
let me tell you what happen when the cartels money flow stops. first phase, it will tip balance of power. large cartel might not be able to keep financing their operation, smaller cartel might find with some routes still working and will have to defend them and in general everyone will need to wrestle a larger slice of a smaller pie, or die. cue widespread shootouts between factions, splintering of cartels, all that stuff.
those who remain will be left in control of a smaller operation, less competition, less emerging competition since it's less profitable to run a route. that will free up lot of assets. that money will be invested, because those people aren't stupid and bloodthirsty, not in the higher echelon at least. and will be invested on the strongest economy, buying legitimate business left and right. pumping money in those business will cause a competitiveness drop of whole sectors, as they need not to be profitable and will be run like your average laundry operation, except on larger scale and working like a legit business under most aspect but financials.
entire segments will become unprofitable for legitimate business and competition will wither, leaving cartels in control of large conglomerate, and that's where real problem starts. normal people will be unemployed unless working there, creating a strong leverage on the employees, driving down wages, working ethics, working safety, etc. once a critical mass is reached, connivance will take place and things will become more overt to the point everyone knows but, as every worker is potentially an accomplice due to knowing, noone ever wants to talks. at this point common people trying to snitch would be the most likely to float up dead.
this all sounds like a 10 dollar thrift store fiction right? except this is what happened last 20 years in Italy when local resources dried up. you can find plenty references around, you might want to start there
http://www.aljazeera.com/indepth/opinion/2016/07/face-mafia-italy-160707105425997.htmlhttp://www.ibtimes.com/welcome-european-mafia-union-how-italian-mob-swallowing-europe-1619110 and work back. of course america is a big, big place so it will never be so widespread to swallow sectors whole like construction and trash management here, but just building a wall is not gonna stop the money flow, whether it actually stop the drug flow (and I bet it wont)