The Ninth Circuit has affirmed the lower court's rejection, on a 12(b)(6) motion, to various provisions of the Copyright Act. Here is a link. (It's the third case on the list). One aspect of the challenge was plaintiff's argument that the 1992 Automatic Renewal Act altered the "traditional contours of copyright protection," requiring First Amendment review. The court of appeals held, that under Eldred, such a review might well be triggered, but further held that Eldred had already addressed whether extending existing copyrights was constitutionally permissible. That wasn't the exact issue in Kahle, but the court of appeals believed effectively they were the same.
The second issue, also not addressed in Eldred, was whether the Limited Times language in Article I, section 8, clause 8, was a substantive limitation on Congress's power to alter durational provisions. It clearly is, and I have gone further in arguing that "to promote the progress of science" is also a substantive limitation. The court of appeals, however also believed Eldred had impliedly reached the issue, and that the question of whether a term was limited or not is a balancing test, one best left up to Congress.
In short, the court of appeals seemed to agree with plaintiff on the approach to use, but rejected the claims on the merits.