In standard usage of the phrase "in the immortal words of...", are there any restrictions on the mortality of the speaker? I typically only hear it used for deceased speakers who once walked the Earth. In my mind it conjures up images of people with great historical significance, but perhaps it's not limited in that regard. Consider the following examples.
Case 1: The speaker is deceased.
In the immortal words of John F. Kennedy, "Those who dare to fail miserably can achieve greatly."
Case 2: The speaker is alive, at least at the time of quoting.
In the immortal words of Stephen Hawking, "Life would be tragic if it weren't funny."
Case 3: The speaker is fictional.
In the immortal words of John Rambo, "I'm no tourist."
Are all of these situations typical uses of the phrase?