I realize that this question may be arguably off-topic, but there doesn't seem to be a stack exchange specific to oceanography, geography, or architecture.
With rising sea level in mind, how high above sea level are the front doors of 'at risk' iconic structures, such as the One World Trade Center in New York, the Opera House in Sydney, and the Shanghai Tower? If it is true that sea level will ultimately rise not less than six metres (albeit not for several centuries hence), then will these buildings all become islands?