Premise: We have a copyright term that's consistent with the concept of the creator plus the creator's first generation heirs. We have a copyright term, remember, which supersedes the earlier copyright provisions that were added to the period between creation and publication, so that the limited number of years in the first, the 1790 and the 1831 statute were the number of years plus the relatively unlimited period of time between creation and publication, so we don't have anything remotely like that in this situation.
Hypothesis: Work created prior to 1790 will have it's copyright dissolved as there will no longer be limits on work that old.