From Nature’s story on the Plan S “Rights Retention” announcement:

“Very few” publishers allow the combination of both CC-BY and zero-embargo sharing of AAMs, says Bianca Kramer, a librarian at Utrecht University in the Netherlands. Publishers often ask authors to sign agreements that stipulate that AAMs can be shared only under a more restrictive licence. For instance, some 2,800 journals from large publishers do allow scientists to post their accepted manuscripts immediately online, but fewer than 20 allow both zero embargo and CC-BY licensing, according to an assessment by Kramer and librarian Jeroen Bosman, also at Utrecht University.

There will ripple effects from the decision—hard to predict ones. The pressure, ironically, for big publishers to go gold OA may decline, for example—since this green route works too, and they’ll have a hard time opting out.

One ancillary benefit: overlay journals (which gather and re-assemble papers from repositories and other OA sources) should have a new forest of articles to harvest.