If you want this post to be discussion about the copyright status of posts on LW, then you should change the title. I expect that a lot of people who would be interested in commenting on that issue might skip over this post because the title gives no indication of the actual topic.

You obviously cannot retroactively change the copyright status of already published posts without the express consent of their authors, but I'd support a move to add a text saying "by pressing submit, you agree to license your post under [some CC license]" to the submission form. Or possibly an option to choose under which license you wish to publish your post, though that would more work for the site programmers.

Also, I hereby declare all of my past and future posts on Less Wrong to be licensed under CC-BY. EDIT: No wait, I can't make such a declaration, because part of my posts are written for MIRI, who owns the copyrights according to the work-for-hire clause in my contract. I'll try to mark these posts somehow, but ask me if you want to be sure.