There's this idea that "because things have been playing out in a way, they'll keep being played out this way", despite the fact the increased means of production (call it "technology") change things fundamentally all the time.
It's very expensive to maintain the military. It's only possible nowadays as governments can impose taxation and due to the currency monopoly they can print as much money as they want to fund that sort of self-preserving activity, which is technically called "debt spending".
As decentralization spreads over, the management costs of taxation skyrocket, and the currency monopoly disappears. Without that governments can't fund their own activities. Which means they'll shrink progressively. As time goes by, they'll start failing at providing law and order, and private companies start providing protection, insurance and private arbitration services to people. Further down the road those companies in their aggregate will start protecting people from the state itself. The state then either becomes a company which some people voluntarily contract services from, or it vanishes.
I'm pretty sure someone would say that the "evil companies" would then merge and become another government, but that's only if that person missed the whole point: in the long term centralization is not economically viable, and in a non-regulated free market environment monopolies are not really possible. As those companies are voluntarily contracted by people, an attempt to fight their customers would be catastrophic as they'd unrecoverably lose their business to competitors.