Does The Success Of The “Harry Potter” Show, A Threat To Broadway?

To some theater veterans, the success of “Potter” — a 5½ hour extravaganza set in the world of a Hollywood mega-franchise — is cause for concern. Is this, they wonder, what it takes to make it here now? Shows based on known properties are mounting an offensive on the New York stage. And some in this old guard worry a sacred American institution — and a time-honored way of doing business — is becoming endangered.