I publish in the field of atmospheric science. The American Meteorological Society journals are the "gold standard" amongst my research peers. While I am not happy with how much it costs to publish and subscribe to the AMS journals (the former is covered by NSF grants, the latter is "subsidized" by the university), all I know as a scientist is (a) I have to publish there to get maximum impact (b) I have to read everything in there to keep up and because the authors will likely be reviewing my future manuscript submissions. If, tomorrow, the AMS journals drastically changed their subscription model - making it open access, dropping the cost to subscribe and/or publish, etc., it would not make a single bit of difference to me, and to probably most other scientists publishing in AMS journals. Everyone would continue to submit and review, because that's where you publish, and if you don't publish there, the "right" people might not read your work.
A major change in the business model for journals would radically affect the journals themselves, and in atmospheric science in the US, the AMS itself which produces the journals. I don't think many of us weather-heads want to see the AMS fail because it does a ton of great stuff (advocacy, education, conferences, etc.), like similar organizations in other fields. But, without us scientists doing peer review for free, all "refereed" journals cease to exist, but so long as you have scientists willing to do the peer review, journals can certainly exist without much staff (many of whom are publishing scientists themselves). So we collectively wield a lot of power should we choose to use it but I personally don't know any other scientists who are willing to die on that particular hill, we're all mostly busy doing our science and trying to scrape some funding together in an extremely competitive environment.
I suspect governments themselves (as was mentioned upthread with the EU) will have to catalyze the real change. Currently AMS journal articles are open to the public after 1 year, with select articles available right away. If NSF decided tomorrow that it was not allowable to ask for more than [dollaramount] of page charges per article in NSF budgets, it would have a real, immediate impact on the problem addressed in the article.
Anyhow put me down as another academic type who definitely agrees that things should change, but also as someone who is not going to spend any time advocating for it simply because it's too big of an issue and I have grants and papers to write (sorry, just being honest here). Switching to a new (read: inferior) set of journals is not a viable option, and that is where the journals wield their real power - we need them (because all the important people read Important X Journal), and they need us to maintain their quality via the peer review process. It's probably going to take an outside force to break the current model; it's hard enough to get funded/tenured/promoted as it is, much less without deliberately publishing in the "wrong" journals.
