The elephant in the room here is the First Amendment rights of the copyrightholders/distributors. They are going to say that they have a right to put out the message they want…and that the First Amendment rights of noncopyrightholders can always be vindicated by redescribing the work they want to use (or using the ideas, not the expression).

Your question about “baselines” here also reminds me of Jennifer Chandler’s and Ellen Goodman’s work on the ways in which Congress can avoid First Amendment limits on media regulation by framing such limits as conditions on benefits–not as flat out regulation. I think Goodman examines the SHVIA as an example of such a conditioned grant of privilege.

Here, the baseline I suppose would be the “traditional contours of fair use.” As in the takings cases–when does the tradition start? Might the copyright expansionists claim that Sony went beyond the “traditonal contours?”

Perhaps something like the Documentary Filmmakers best practices thing is a good example of a “hard core” of fair use….something nobody ought to disagree with, well within the “heartland” of the traditional contours of fair use (to use sentencing jurisprudence patois).