Among “other arrangements”, one obvious extreme is lump subsidy and no access restrictions. This gives maximum society benefit at a fixed price. Other arrangements are “some subsidy + other revenue” which is exactly the model that PLoS explores. And which should be explored. And which does not need to be successful by the same measures as Nature was successful in the past.
And as a personal opinion on this – I think that what will (and should) happen is that the market (lead by initiatives like PLoS) will drive costs of top-tier publishing down. Future top-tier publications will simply have to have unbundle, have less costly content, and less costly procedures – and will consequently look different from today. I see an obvious analogy to newspaper-publishing which was discussed at the Becker-Posner blog recently: Posner – Becker
So, if you buy my view of the “framing” aspect. Then it is worth noticing that both Nature pieces had the same framing of the problem. And that buzz around the obviously confrontational and distorting first piece helps take focus from the problem framing, and put focus on the more obvious silly points. And generating buzz – even negative buzz is the objective if “framing” is the goal.