I love Zeihan's honesty, wit, and optimism. Was that sarcasm? Not really, he's bullish on the future of the USA despite some unwarranted pessimism about the future of the world. "Dear is Plato, dearer still is truth".
Zeihan's insights into the hydrocarbons are deep, accurate, the best going. He has a solid grasp of geography's role in strategy and a decent understanding of militaria for a civilian. He's even better than Mearsheimer. Both are a bit too deterministic: Mearsheimer is a sort of Hobbesian determinist, structural realism compels us into suboptimal situations, per Mearsheimer. Zeihan addresses this only indirectly. Instead of a psychological determinism Zeihan's is driven by demography and geography. Unfortunately, he overpowers his determinism. Material factors do shape state actions, but ideological factors, i.e. free will and choice, often over-ride them.
Zeihan's analysis of Russia is more accurate than most, in other words inaccurate. He propounds the theory that Russia faces demographic collapse and does not control land-access points and thus is indefensible. To his view then Russia was compelled to war; it's a bit of a self-fulfilling prophecy which ignores the fact that Russia has repeatedly won defensive war after defensive war on its own territory thanks to defensible terrain: many very wide North-South rivers, 5 or even in places 7(!) months of winter (Oct-April), and vast distance makes the Russian state quite defensible. All the oceanic access points freeze up most or even nearly all the year. Russia is quite defensible, just ask Napoleon, Hitler, the Swedes, the Poles, the Chinese, basically ALL of Russia's neighbors have at time tried -- and failed! -- to conquer it.
While it is certainly true Russia was subjected to a near extinction event from 1933-1945 the entire first world faces demographic decline. The idea that these factors compel aggression feeds right into Putin's myths, and it's simply untrue.
Zeihan is, despite his demographic determinism and geographic fixation worth reading: not because ideology is pointless or meaningless, but because he at least grapples deeply with serious issues, notably issues in energy markets, where he is The Best Civilian Analyst bar none.
Zeihan however underestimates the capacity of the USA to reign in China, notably the Xi Jinping faction, its tenacity as a global hegemon. He predicts a sort of neo-isolationism when in fact what we will see is ... a new cold war.
I hate to be the harbinger of more death and destruction. I expect the USA will quickly contain Chinese over-reach and that the politburo will reign in the cult of personality and that their mutual greed will compel the USA and China to play nicely economically despite a serious, but avoidable, national security rivalry.
Zeihan, like Mearsheimer, wrongly believes we are constrained and compelled, that we are painted into a corner, whether by the anarchical structure of international society (Mearsheimer) or compelling material factors of geography and demography. In fact those are mere constraints, they incline toward certain outcomes but do not compel them. To understand those constraints' existence, something U.S. foreign policy ignored for 20 years since 9/11, you should read Zeihan. He writes well.