Land isn't the problem, even in suburbia large commercial complexes fail all the time or rich people get some grand ambition to build their perfect city outside of the existing one. For example Las Colinas outside of Dallas. Or Rosslyn outside of Washington DC. These were planned in one go to be the ideal future of urbanism at their respective times, and there are many other examples beyond these. The issue lately if the local opposition is small or poor is zoning requirements and parking minimums drastically increasing costs.