Siezing power through coersion, whether its informal through armies, gangs and mafias, or formal through kingdoms, theocracies, republics or democracies, is a persistent threat. The state of anarchy is always temporary until one of those comes along and promises protection in exchange for a fee, voluntarily or not.
Discussion
Everything is temporary, nothing is eternal. That case, seen as just another company, from my perspective ANCAP would probably disappear, it would generate little confidence in the market and at least as a defense company it would not be able to survive, no one would hire its own executioner