Preamble
Being impressed by what I have seen of Humankind thus far, I wanted to share with you all some praise, coupled with my thoughts on how I believe a strong economy simulation might benefit the game.

-The unique 4X Problems
Business requires balancing “scale” with enjoyability through the ages both for casual and hardcore players.
That's obviously really hard, Not just on Systems Requirements but game design, most 4X games do suffer from that mid-to late game “slump”, where many a playhtrough ends, usually because of a combination of diminished challenge and the micromanagement tedium of managing mechanics (that are fun in the early game) that comes as function of size!
 

Solutions certainly have been tried (with varying Success), CIV-4 had city & Worker automation, Stellaris has Sectors and Governors, CIV6 works around the issue by cost inflation, diminishing the ROI of civilian expansion in order to prevent for Micromanagement from spiraling out of control, that game design decision however comes at the expense of “Role Playing”, as it does not make much sense to have inverse economics of scale, makes becoming a “Superpower” untenable, and furthermore forces you to play the game with a straight line focus to your chosen victory condition.

Humankind's “Fame” System might actually manage to put the storytelling and thus the Journey itself front and center by removing the abstract pressures of working towards an abstract end-game goal* and instead focusing on the immediate future, keeping the player well aware that keeping up is important.

The Map Mechanics

What the mechanics that we have already seen in Humankind seem to represent is an attempted solution to typical 4X Problems.

Instead of trying to keep the exact same mechanic interesting from a Tribe of thousands, over an agrarian society, up to an interconnected World of Billions, Humankinds concept of Tiles > outposts > cities and regions allows for a fluid change of "focus" through the Eras, from potentially navigating the surrounding Tiles with unease during the “Hunter Gatherer Time”, before settling your first city, to a Focus on the Management of City-Districts and a “game of life” of incorporating minor tribes (I really like that idea) in the early game, to a focus that's then slowly shifting to the big picture stuff, managing your culture and strategic interests, looking more at “regions” than the individual cities therein.

The Economy and Trade and Industry

Trade was and is central to the History of Humankind, it influenced  almost every important decision played a major role in most wars and more often than not decided the victor.

I therefore believe that trade, and the emergence of civilian manufacturing and industry, should  play a major role in the evolution of Humankind and reflect the players choices as well as geographic luck, it must of course do so remaining organic and mostly hands off as to prevent a “Spreadsheet” game, but done properly it can not only make for an extremely rewarding experience but also make AI Decision making more rational. 

The Player should, by their action, steer commerce.

• By zoning Industrial and Agricultural Tiles, As well as ensuring access (and improvement off) resources.
• Building transport infrastructure (Roads, Harbors, Dockyards, Railroads, Airports) 
• keeping up with technology (improving yields and gaining access to new trade goods, perhaps ahead of others) 
• The (Cultural or Religious) Appeal of cities
• Trade policy and Diplomacy

The Players control over non-strategic resources should however not be hands-on, as in the Civilization franchise, rather inspiration could be taken from games like Paradox Victoria 2 or the Mathematics behind the Economy of games like EVE Online. To be clear, I am of course not speaking of simulating a "true" closed loop ingame economic simulation, merely an approximation.

A few rough thoughts on how such mechanics could work and by virtue of their implications benefit the game experience.

• Every Luxury Resource (in the Late game this could even include consumer goods) will be, depending on the players choices, allocated by the trading “agents” based on a simple algorithm that weighs Demand/Subsidy (The Populations Demands as well as the Players' interaction with the Market) available transport routes (Expenses) the players trading policies (Ban/Taxation) an "inertia" factor (scaled by difficulty, to prevent rapid changes) and perhaps other factors.
• The Player can Influence Trade, support it by building Commercial Hubs, Ports, Dockyards, Interacting with non Player Factions, ensuring Free Trade with other Empires, securing vital resources for his own Civilization, or subsidizing valued Capabilities or Imports to ensure a happy population. 
• The Player should be able to "embargo", blocking others to trade through and with you, choosing to not trade resources, costing him gold but lessening dependence on others and perhaps mitigating "tech diffusion" making any technological edge last longer. 
• The AI can be used to interact and nudge the Player, this helps in keeping the game accessible as well
• "Trade Routes" might be displayed as a Map Layer, with the different "streams" connecting hubs such as cities, allowing the player an easy overview of the dynamic trade network.
• Trade Interconnectedness and level of self-sufficiency can be a great help in the AI decision-making algorithm, preventing erratic AI behavior by incorporating easy to gauge metrics.
• The System could, by adjusting the distance cost and other multipliers, be made to work mostly in the background, requiring little but open borders with your neighbors to prevent trouble on lower difficulties but requite the player to pay closer attention to their trade policy on higher difficulties. 

• Macro not Micromanagement, except where attention is warranted
  • No need to constantly hop around the Trading Menus.
• Choices can have clear, short & long term, consequences
  • Focusing on exports might be good for the Treasury but your people might resent Mercantilism, your cities might grow in importance and population as trading centers or decline due to unemployment or even famine (simulating the true rise and Fall of Cities).
  • Building up Industries, such as Dockyards, could not only be good for building military naval units but also allow for your CIVs Trading Agents to build a strong merchant marine (lowering the transport cost Multiplier), which might in turn make building navies both cheaper and more important to your interests.
    
  • Being Expansionist might run counter to the stability that trade demands, somwehat balancing "tall vs wide" play styles.
• Decisions, Technological Advantage and long term behaviors matters
  • Being a comparatively technologically advanced CIV might put you in a position where your economy might be more productive or offer consumer goods that others cannot make themselves, thus boosting exports, at least until others catch up, but on the other hand implications such as emigration of manufacturing entities or resource dependence might occur.
  • Depending on a neighbor for Cheap Food can free your economy up for other Tasks, such as building great works and manufacturing, but put you in a position of dependence, even danger of starvation.
  • Being a large and influential civilization can put you in a position of dependence on others, as your stability hinges on the stability of the trade with your neighbors and the wider world.
  • Being isolationist can have short term economic, and Military benefits, but cost you in the long term as the economy of the world evolves around you.
• Balance is potentially improved and the World makes more sense, both for the AI and the Player
  • As a major force you are forced to intervene choose sides and/or try to prevent conflicts that endanger your trade and while your leading role might lead the world into an age of "pax-insertyourcivname" earning you Fame as a bastion of stability that military focus might well give others the chance to catch up, perhaps even eclipse you. 
  • Military conflict could be given reasons other than pure expansionism, leading to a game that has something like the opium wars, forcing others into trade with you, or securing vital supplies without which your sprawling population might starve or energy resources without which your industry would come to a halt. 
  • Being a Hub of commerce may lead your cities to grow rapidly via migration from other empires, but invite both religious, cultural and political problems.
  • The Late game implications work for both Tall and wide styles, while playing Tall you might still want to micromanaging tiles, improve efficiencies and find your niche, playing wide forces you to focus more on the Macro aspects of your Empire, the world as a whole, and view micromanagement as unnecessary as size and Influence balances out the inefficiencies and redundancies of a sprawling Empire.

Thanks for reading my Fanfiction :-)