I don't know for sure, but I'd guess that the vast majority of NPG's revenue comes from institutional subscriptions and that the vast majority of those institut

I don't know for sure, but I'd guess that the vast majority of NPG's revenue comes from institutional subscriptions and that the vast majority of those institutions make use of NPG's review/editorial process. I guess there's less of a notion of the accumulation of valuable property in the pay to publish regime. But seriously, just call the subscriptions "membership fees." Revenue would probably dip 5% from non-publisher subscriptions and things would stabilize. It would also neutralize the threat of open access journals gaining more ground.