We know that Hollywood doesn't like originality anymore. It was always wary of it - even back in its dawn - but these days The Studios' money men display a genuine allergy to anything that they think doesn't come with a built-in fanbase.
Consequently, Hollywood has spent the last decades on a campaign of IP mining that borders upon grave robbing. Sometimes (True Grit), a great film comes out of it. More often (Clash of the Titans), we're left wondering show could possibly have thought that a good idea.
What's a film no one should ever dare sully with an update?
I vote Casablanca. That was such an accident of actor chemistry, ad hoc script revision, and the events of the time, I don't know that it could ever be replicated with justice.