If you'd bothered to read past the catchphrase you'd realize how stupid this sounds. It would also help if you gained some perspective on Mexican history - it's never been an issue of lack of funding for police.
This seems unlikely. It would vary a lot by the society in which “Defund the Police” became policy. The last time the US decided to radically reduce law enforcement and severity of punishment for law breaking in the 1960-1970 period it didn’t lead to parastatal organizations with their own militaries. Eventually the public grows sick of the disorder and laws and constitutional barriers that militate against harsh punishment and enforcement get worked around. Before the political reaction you had a broader social reaction in the flight from cities and suburbanization.