An important but as-yet rather underspecified part of the Plan S is to find different reward structures that remove the pressure to publish in "prestigious" journals and move to a system that mainly focuses on the quality of research. It will be interesting to see what they come up with here, and whether that will be successful.
(Disclaimer: I am working on a project that hopes to improve the prestige for open access publications and preprints.)
I think all of this is generally a step in the right direction but am worried about where it is leading, for two reasons:
1. My experience with the frontiers of open access science in my field have been concerning, in that it seems to feed even more off of the social media hype-TED-talk branch of academics that I see as just as much a problem. That is, with traditional closed publishing, you have lack of access to the public and lack of transparency which seems unacceptable, but with very open access platform things can turn into a petty social media popularity contest. Yes, you get your stuff out, but the dynamics can be very different and feel more like a glorified flamewar ala reddit or old-style USENET groups.
Related to this, I think the way peer review plays out in different fields is very different. So, arXiv stuff might seem normal in comp sci, math, stats, but if you ever want to see uptake of that in an applied field, it had better have a rubber stamp of peer review or no one will touch it.
2. Unfortunately, at many universities, at least in the US and the UK, the pressure and nonsense has moved (increased?) from publishing from prestigious journals into grants. That is, the power structures underlying this all are indirect costs (in the US) subsidizing universities. The problems with this are problems in the way grant monies are allocated and awarded, the kind of "slush fund" quality of the indirect costs that afford universities profits, and the vast inequities across disciplines and topic areas in terms of what requires funding and what is popular at any given time (some research, for example, just requires less money to conduct; this should be a good thing for research funding, but is a bad thing from the university perspective because there's less indirect money to siphon off of).
The reason why I bring this up here is because I think the publishing problem and grant problem are kind of linked, but in a way that makes the open access issue kind of missing the target in terms of where the big problems with academics currently are. I worry, for example, that if you move to a model where everyone just publishes whatever anywhere, it turns academics into a giant flamewar, decreases the value of good research per se even more relative to grant receipts (because it's all fuzzy anyway and everyone can post anything to arXiv), etc.
I definitely think academic publishing needs to become totally open. But my current sense is that there isn't a good infrastructure to replace it in many fields, especially the biomedical fields, and pathologies in those areas will just sort of rip what's left of its integrity apart.
(Disclaimer: I am working on a project that hopes to improve the prestige for open access publications and preprints.)