My work is still in progress, so I agree that some aspects could be quite simplistic.

1) I think suburbs exist because there is a market strategy behind them. Any retrofit proposal should have its own market strategy as well. At the moment, downtown is a good product for young, single professionals: how could it become a good product for families too?

2) Many communities already exist (for example, the Couchsurfing community), and some of them are starting to create real spaces (they have a “flatsharing” group). How will this trend go on? will it expand and create entire neighborhood?

3) Till now, both public bodies and developers were stick to the “big house+ car” model, and cooperated in creating it. By now, public bodies are starting to think about walkability issues, but many developers are still stick to the suburban model. Probably, in a while somebody will try to promote walkable communities too, and things will change.

1. you don’t pay attention on why still people prefer suburbs to city centre, even though suburbs are dead, non human-friendly, etc, etc.

2. it is really difficult to create crowdedness even in the most dense city centre of the world. I mean, you perhaps can get congestion but it doesn’t mean that people are collaborating each other. Community, I think it is what do you mean with Crowdsourcing, is nowadays a rare source.

3. To improve street, sidewalks, greenpaths, and so on you need dollars $$$. Now, it seems that public bodies do not have this $$$. Thought, are the developers who should act in this sense. But developers don’t care at all for puplic infrastructures because it is supposed to be a government issue. In other words, there is a kind of mismatching on who should do what and with whom’s money