This is actually something I liked in contrast to earlier futurism. If I look around me here in Europe I see that buildings rarely get removed once they stand. The last time the face of cities here changed was after the Second World War. If I look at pictures from the 60s rarely anything changed, except maybe the introduction of some pedestrian zones.
That seems overly broad - a surviving old city tourist area might be well preserved but elsewhere, post-war city rebuilding programs were cheap, rushed and ugly. Even later development is unloved because "high-design" of the time was infected by Brutalism. These already troubled urban centres were then hollowed-out by economic troubles in the 70s leading to areas of dereliction.
Over the past few decades, urban regeneration programs have been widespread to remove the bleak post-war prefab concrete monstrosities. Unfortunately what is replacing them is cheap and uninspired compared to pre-1900 architecture so I can't see us valuing it that much in 100 years.
That isn't true. We protect valuable architecture with preservation orders. Usage isn't really a factor - tenants of actively used buildings will be given notice and the site redeveloped if doing so is legal and profitable.
This is actually something I liked in contrast to earlier futurism. If I look around me here in Europe I see that buildings rarely get removed once they stand. The last time the face of cities here changed was after the Second World War. If I look at pictures from the 60s rarely anything changed, except maybe the introduction of some pedestrian zones.