That's not the big challenge. Upzoning and higher density increases the value of the land. That's why developers want to do it in the first place. Cashing out when someone wants to buy up your neighborhood's land, and getting something nicer somewhere else, would be the purely-financial play.
The big challenge is that people chose to live in a certain place because it had certain features. And people don't want to have to move constantly. So folks pushing to change the nature of the areas will always cause opposition ("why do we have to leave or change, why can't they go somewhere else?").
That's a very short curve that quickly inverts. Density of commercial land is what converts the sprawl to an unprecedented explosion of high-rises in an epicenter. The residential density decreases the value of the land after it's been fully developed, which is then purchased for commercial use and "redeveloped". This happens in most cities at some point, where downtown is converted to the new "hip" redevelopment of the previous slums.
> The big challenge is that people chose to live in a certain place because it had certain features
In Germany, the most sought-after features are quality mobile ans landline internet, as well as decent public transit.
The problem is that our Conservative politicians outright sabotaged (Kohl with fibre vs cable TV, Schröder with the UMTS frequency auction) or, at best, simply sat doing nothing (Merkel) any efforts to improve this situation.
The result? Everyone who can flees for the cities, while the rural areas generally only house those "left behind".
And then politicians complain about exploding rents in cities or people leaving rural areas... well, d'oh, who would have thought young people and modern jobs require Internet.
The big challenge is that people chose to live in a certain place because it had certain features. And people don't want to have to move constantly. So folks pushing to change the nature of the areas will always cause opposition ("why do we have to leave or change, why can't they go somewhere else?").