Funny. First off, why are these "megacities" inevitable?
Is it perhaps because all money flowing through the economy ends up coincidentally in large financial centers?
Is it because government owns most of the land?
Is it because "it's just too crowded and depopulation needs to happen"?
Secondly, even if it is the case, why are these megacities destined to be, "urban hellscapes — brutal and anarchic supercities filled with gangs of youth-gone-wild, a restive underclass, criminal syndicates, and bands of malicious hackers"?
Is it because we're being looted and ruled, herded into these places as result of a deliberate plan? Maybe not the latter. But we are being looted and ruled by psychopaths, who do not have one bit of remorse or guilt for the pain and suffering they inflict on others.
Perhaps it's because they know full well that the central bank booming/busting/fleecing of the population is going to lead to a complete and total breakdown of society. And of course, whatever society looks like, they know they're going to want to kill people, so whatever the landscape of the killing fields might be the Pentagon wants to be ready.