The Guardian contrasts the teardown fate of two Miami homes and discusses how preservationists want to set new guidelines:

City of Miami Beach figures show that from 2005 to 2011, only 20 requests for the demolition and reconstruction of architecturally significant pre-1942 homes were submitted; another 20 more came in for the calendar year 2012; and from January to October 2013, the latest period for which figures are available, a further 40 applications were received.

James Murphy, principal planner for the municipality, described the trend towards development as “off the chain” and said that the city’s Design Review Board, the ultimate authority in decisions of destruction versus preservation, was trying to keep up…

The preservationists, meanwhile, have been here before. The Miami Design Preservation League, which fought and won a battle in the late 1970s to save the curvy art deco facades of Miami Beach hotels and condominium blocks, is eyeing a way to convert what it claims to be a groundswell of support over the Hochstein villa into new legislation.

It is discussing with city commissioners a proposal that would require any application involving a property more than 50 years old to automatically go through a formal review process before demolition could be approved.

The two stories presented are interesting ones. The first involves a wealthy owner moving an older house on the property and restoring it. The second involves a wealthy owner finding an older house with lots of problems, leading to its demolition and the construction of a 20,000 square foot home. Should both cases be subject to the same rules? Presumably, preservationists would develop a whole set of guidelines that would dictate when owners could and could not make changes but I do wonder if they would prefer that no old homes are demolished for any reason.

Side note: here is the definition of a McMansion in the article.

Already going up in its place is a 20,000 sq ft waterfront palace, complete with an enormous games room, walk-in wine cellar and 17-seat cinema. Such oversized homes, frequently occupied only by successful professional couples or their small families, have become known as McMansions.

The luxuriousness of the home may lean toward a McMansion but (1) the size is simply too big (this is a mass-produced tract home) and (2) it is relatively rare to discuss what kind of family structure is present in a McMansion.