Building residential areas indoor (including parks, streets etc.)
Our cars and houses create atmospheres we desire, there are nice cool malls in the middle of the desert (Dubai) and warm ones in Helsinki, Tesla cars have HEPA Filter to protect against particulate matter pollution and a large portion of our food is grown indoors. If we can create the best possible atmosphere for almost any kind of plant why don't we create the best possible atmosphere for ourselves everywhere!?
Today I stepped outside (Holland) and it was raining like it often does. I don't like rain and that is why I bought a house with a roof over it. I bet my neighbours feel the same as their houses have roofs too. Why don't our streets have roofs then? And our parks? Lakes?
I tweeted this question and someone responded this retro-futurism picture:
Imagine the situation above but with a glass roof. There is an optimum amount of light and UV for human beings. I don't know what it is but we can find out. The same goes for temperature, convection, humidity, thermal radiation, C02, oxygen etc. What if we create an atmosphere under our glass roof that is ideal for us. Wouldn't that be great. A glass roof with interactive solarpanels and LED lights for ideal UV and light, filtered air, a balanced amount of plants for an ideal C02 to oxygen ratio, fountains for ideal humidity and have our cars run underneath so we don't breath their pollution .
I am pretty sure this bound to happen, it's more a matter of time. To elaborate on your 'optimum social cohesion' subject we can also manage crowd control like this: every human has a sensor and rooms automatically determine through data analytics when there are too many people in a room. This could automatically disable doors that lead into the room and keep the exit rooms open so people can get out. That way we can also deal with overpopulation..
I am glad you think it is bound to happen. Can't wait. I like the idea of having sensors to optimise things. Just like Google Maps does with roads it could warn of certain parks being overcrowded and suggest another.