Well, you’ve asked the right person. My company just finished some work at the foundation. I have been up and down that place, I know it well.
The Empire State Building, and buildings like it, will last as long as there exists a civilization capable of maintaining it and willing to do so. Every component, every steel beam, brick, and Indiana Limestone block can be individually repaired or replaced as needed, and many already have been.
The elevators upgrade was very recently completed. The second time. In 1966 they went from manual to automatic operators. All the exterior lights were recently replaced with a new automated LED system. All the windows and the air conditioners were also replaced.
Of course there is a philosophical side to the question. If every part is replaced, is it still the same thing? I say, yes. “Continuity of Identity”.
A number of you have asked how a steel beam or column can be replaced in a building. I covered this in one of the comments. The important part is the installation of the temporary shoring and bracing. This is a shoring plan for a corner column presently being replaced at an NYC building.
