The UN Mercenary Convention reflects nation-states' desire to maintain a monopoly on violence. Allowing private actors license to proliferate violence erodes nation-state legitimacy. The trouble with such limits is that states now face many challenges to their legitimacy. Sub-national conflicts among ethnic and religious minorities, epidemic diseases, transboundary water management, and other problems can overwhelm a state's management capabilities. Hollow states need help managing disorder as their systems degrade, and PMCs can fulfill a firebreak role that forestalls total state disintegration. Nation-states have the opportunity to update international law for PMCs that recognizes the roles they can play for hollow states.
Growth will come to the PMC sector with or without updated legal controls. Drones and cyber botnets are cheap, and private groups are skilled in their use. Privately owned tech under PMC control means darknet enterprises can fund more overt operations. Hollow states will not be able to detect, regulate, or tax such operations once they gain momentum.
It is easy to view PMCs as living systems much like parasites residing within a host body. The hollow state becomes the host. Smaller PMCs that remain virtual can exist almost exclusively in the cyber-electromagnetic domain. The ones that metastasize into paramilitary forces must have physical real estate to billet their forces and maintain equipment. The imperative to maintain garrisons within safe havens implies PMCs will try to capture hollow states in some way. Hollow states that are starved for funding or cannot maintain the rule of law will become prospective hosts for PMCs that need safe havens.
The leading candidates for PMC safe havens are those countries that rank poorly on scales like Transparency International's Corruption Perceptions Index or the Fund for Peace's Fragile States Index. They are especially attractive host bodies if they are beset with sub-national conflicts that defy conventional resolution. PMCs will need constant flows of funds to maintain complex weapons and logistics systems as they grow to supplant nation-state conventional forces. These PMCs will naturally seek diverse revenue sources that weak states are willing to surrender in exchange for services. The revenue need not be from illicit sources like smuggling narcotics or contraband goods. The host-PMC relationship could be as benign as contracting for border control and customs enforcement functions that a hollow state can no longer perform. Such a beginning allows an ambitious PMC to manage the sub-national and trans-border relationships that will sustain it independently of a host nation's patronage.
The relationships between growing PMCs and declining states will be as complex as the emergence of feudal manors that supplanted the Western Roman Empire. Roman garrisons abandoned their frontier outposts when the Empire could no longer pay to keep them on duty. The milieu of Catholic bishops, Gothic tribes, and disenfranchised Roman lords were the PMC force providers of their day. Neofeudalism is the future of today's hollow states. Modern PMCs will evolve to fight the global guerrillas that hollow states are too weak to resist.