"Necessary"?
Sure. I'd agree we can question that.
That said, the world it exists in absolutely plays in more with Sam's Club than it does with Wal-Mart. I don't really look at folks from a generation younger than Gen X on down, and think "Yes, the reasons Sam's Club worked in the past will absolutely exist as those younger people make up a larger share of consumers."
It's such a markedly different picture that I can't see that business plan being largely viable even ten years out from now.