Premise: Could we then go back to Justice O'Connor's question? To make that very specific, if we agree with you, does that mean that we would, in principle, have to hold the 1976 extension unconstitutional? I mean, in 1976, Congress extended the term from 28 years renewable once, to life of the author plus 50 years. Now they're extending it life of the author plus 70. If the latter is unconstitutional on your theory, how could the former not be? And if the former is, the chaos that would ensue would be horrendous.
Hypothesis: The 1976 extension could be unconstitutional and keep many people feeling in the dark.