Survival of uncertainty, or uncertainty of survival?

On Sunday, February 3rd, Peter Suber, on his Open Access News blog, wrote in his comments to a post by Kevin Kelly, that "[new] business models aren't just good ideas, for example, to make OA possible. They are necessities for survival. For publishers, self-interest should be the primary driver for OA."

I fully agree with Peter. I have always approached open access publishing with this as my adage. My previous posting is pointing to some of the ways in which such new business models can develop.

However, a large and prominent school of thought in OA advocacy seems to argue the opposite. Namely that publishers aren't threatened by OA. "Look at physics", they say, "and you'll see that even though almost all articles are freely available in ArXiv, and have done so for more than a decade, subscriptions to physics journals survive as if nothing has happened."

Now, is OA necessary for survival, or not, since there is no threat to survival at all? Are these opposing views a sign of OA-diversity, or a kind of quantum effect like Heisenberg's uncertainty principle?

Jan Velterop