Zeihan predicts multiple things:

• Dollar getting much stronger compared to any other currency, but still with really high inflation over next 5+ years.
• China will collapse in the next 10 years, especially because of demographics - they are losing millions of working people every year (which is the same for most other countries, USA+Mexico are not in such a bad situation yet).
• There is going to be a massive famine, especially in Africa, for combination of reasons
  • Current grains are stuck in Russia and Ukraine and are already starting to miss on the market
  • Ukraine is not going to plant enough for next season.
  • Because the oil delivery from Russia and Ukraine is getting stuck and becoming weaponized, there won't be enough of fertilizers made and delivered around the world.
  • USA doesn't care about establishing oil routes anymore, since it became self sustainable especially thanks to shale oil.
  • So this is bound to result in a massive famine with a 500+ millions of people dying.
• USA is self sustainable in terms of food (it exports 30%)

If any of this is correct, then yes - USD will perform the best out of fiats, but this also screams like a massive opportunity for Bitcoin.