10 Rockefeller Plaza was built in 1940 so the escalator could be original.

The London Underground replaced its last wooden escalator only 11 years ago and that was more than 80 years old.

(I should clarify: the treads were wooden but the mechanism was steel.)

I bet it would be outrageously expensive to replace. Escalators aren't cheap to begin with and this one is no doubt built to its own standard so anything you replace it with would have to be heavily customized to fit.