It hasn't already?
Not to the degree it is being fought in Mexico. News reporters and police chiefs who are openly against the drug gangs are slaughtered and their bodies dumped in public. Much of the violence is reportedly perpetrated by corrupt military and police. Mexico is a morass of corruption with gang warlords greasing the palms of politicians. Their war on drugs really is a war.
They are every bit as much (or more) of a failed state as Iraq.
It's not clear that democracy is doing much to fix this, in Mexico, either.