Earlier quoted context omitted.
Did you read the article? That's not what they're doing. They're replacing the contents with a link that eventually stops working. Nothing is being changed in the recipient's e-mail interface.
Did you read the OP's post? They're replacing the contents with a link that eventually stops working for you . Nothing is being changed in Google's backend, so the original message can be preserved for as long as they desire.
The headline "Google is allowing you to hide emails from its public interface after a specific amount of time" implies that this is just a change to an existing interface and would only work for recipients who use gmail.