The Archaeological Institute of American ("AIA") has sought to reassure us it is not anti-collecting. Rather, according to various pronouncements, the AIA purports to only want collectors to purchase artifacts with provenances dating back to 1970, the year of the UNESCO Convention. See http://www.archaeological.org/webinfo.php?page=10421
If so, the 1970 date may very well not be much of a "safe harbor"now that the US Government has repatriated an ancient Egyptian sarcophagus at a ceremony conducted at the National Geographic Society. See http://www.ice.gov/pi/nr/1003/100310washingtondc.htm According to some reports, it left the country over a century ago. See http://culturalpropertyobserver.blogspot.com/2009/03/egypt-demands-repatriation-of-coffin.html
It's understandable, but nonetheless too bad the owner of the sarcophagus merely abandoned it rather than spend the money on lawyers to fight the forfeiture in Court. It would have been interesting to see if the basis for the seizure would have stood up to judicial review.
In any event, while the AIA's "Archaeology Magazine" has reported on the repatriation, see http://www.archaeology.org/news/?p=560, as far as I know, no one associated with the archaeological community has questioned whether the repatriation will undercut any faith collectors might have in the "1970 Rule" as a some sort of safe harbor.