What are the forces that will shape it?
Let's assume several lessor O'Neill colonies are established (up to about 100 people per station. Each costing about $50 million per person or about $5 billion per station. Much less than the $150B ISS which can only hold half a dozen.) Some in earth orbit, some in lunar orbit and some at the Lagrange points. Also assume some trade ships owned and operated by individuals with crews from one to a dozen (about 5 ton per crew. Cargo capacity being limited by fuel capacity.) We also have slow, high Isp, unmanned tugs.
Each ship and station will have a captain, the rest are crew. Why not a democracy? Show me any successful ship run as a democracy! For the sake of argument, let's say the stations are a democracy with elected leaders. Those leaders act as term limited captains.
How does this work? Everybody has abundant energy, that's a given. Recycling will be less than 100%. There will be trade that includes the cost of the rocket equation.
Ships will need provisions, fuel and amortization costs (20 years at perhaps a million dollars per month) which is paid for by trade profits. Stations will require bulk imports which they turn into trade goods between colonies. Unmanned tugs will be limited to probably manned destinations able to process asteroid materials although automation will have its part.
Two things should be obvious. Getting people with required infrastructure in space will cost more than the one time cost of delivering people to mars, but let's say it's the same $50M per person. Operating costs in space will be relentless (you simply can't ignore the rocket equation.)
Habitats on mars should have zero amortization costs. They will be fully paid for by the mass allotment of each incoming colonist. They will be built by local labor using local resources. A habitat on mars might cost $100K in labor and materials. A single laptop computer brought from earth could pay for that. Space habitats will cost about $50M per person.
In the far future, O'Neill cylinders could bring those cost per person down, but not in the near term. Cost to mars will also come down, but at a much quicker rate (let's see what Musk has to say this September?)