Radio Free Meredith

I don't think I understand your concern, because fair use ("fair dealing", in Canada and other places) is already a well-established part of federal copyright and trademark law. Title 17, U.S.C. section 107:

Notwithstanding the provisions of sections § 106 and § 106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include:

1. the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
2. the nature of the copyrighted work;
3. the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
4. the effect of the use upon the potential market for or value of the copyrighted work.

The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all the above factors.

This language was actually introduced into federal law as a result of the 1976 Copyright Act.

Furthermore, the two issues really appear to be completely orthogonal -- without language to explicitly remove the "fair use" clause from federal law, fair use holds, whether on an orphaned work or a non-orphaned work. I'd certainly recommend examining any proposed orphaned-works bill carefully with regard to its impact on fair use, but I do not believe that an orphaned-works bill is necessarily detrimental to fair use. Nor do I think the Copyright Office has any desire to destroy the fair use doctrine.