I'm going to have to disagree here.
All of Al's best songs are parodies of classics:
"Another One Bites the Dust"
"Like a Virgin"
"Smells Like Teen Spirit"
I'd bet most of these songs will be all but forgotten within ten years. And the parodies will go the way of "Amish Paradise" where the parody outlives the original. And while it's a funny song, it's nothing compared to the parodies of those I listed above.
I hope you're not referring to those 5 songs when talking about "these songs will be all but forgotten"... they are actual legit classics. Hopefully you're talking about some of the other songs like Blurred Lines, Royals, and Happy, which I don't see becoming classics.