However, my vision for the perfect city is quite different than OP's.
My ideal city:
* Density is between 5k-8k per square mile (twice as dense as Palo Alto, half as dense as Cambridge, MA)
* The density and layout should support a high walkability index. There should be a grocery store, barber, coffeeshop, pharmacy, etc, within a half-mile to a mile of most housing.
* Housing arranged in blocks, with a shared yard for all people on the block. So each house would have a small patio owned by the home owner. Behind that would be a collective yard/green area shared by all the neighbors on the block. This shared area might have a basketball hoop, swimming pool, jungle-gym, soccer nets, BBQ pit or whatever the residents wanted. It would be behind all the housing, and thus insulated from the city. The block should be small enough that pretty much any parent can look out their window and see their kids playing. Basically, any parent should feel perfectly safe just letting their five-year old kid play outside in the common backyard with other kids.
* The road system should be optimized around bicycles, scooters, and microcars (like the Carver or Automoto, because bicycles are not so good for older people in the winter). Roads would have two narrow lanes in each direction, a left-hand lane for 25MPH scooters and roadbikes, and a right-hand lane for slower bicycles and roller bladers. Cars would only be allowed on main arterials, driving a car on the bike roads would require a $10 per day special pass. Optimizing around bikes and mini-vehicles allows for getting between point A & B very quickly, but limits congestion, pollution, and the expense of a full-sized car.
Things I don't like about OP's dream:
* it feels to claustrophobic. I like green space.
* walking is just much slower than biking, so I prefer biking.
* it is really not pleasant to have both bikes and mopeds using the same narrow streets. One of the least pleasant aspects of traveling in a a classical city core is having the mopeds buzz by you at 20MPH.
* row housing looks nice from the outside, but severely limits the amount of sunlight coming inside. I greatly prefer standalone units that have windows on all four-sides.
* In general, I think that very dense, old school cities can be more pleasant to visit for a little while, than to actually live in long term. There is a reason why most people in those countries do not wish to live in such housing or build more housing like it.
The biggest problem in general with doing a city-as-a-startup is jobs. Due to the winner-takes-all nature of the economy, the highest paying jobs are concentrated in a few metro areas where the big winning companies reside. I'm not sure how you bootstrap the economy of the new city.