GSP is scheduled to expire on 12/31/2020. Importers benefitting from duty free treatment will have to begin paying duties on shipments arriving on 01/01/2021. Historical, GSP has been renewed and has been retroactively extended from its original expiration date.
Excerpts from the Congressional Research Service:
What is the GSP? The Generalized System of Preferences (GSP) is a trade program that provides nonreciprocal, duty free treatment for certain U.S. imports from eligible developing countries. The GSP is the largest such U.S. program; there are other regional preference programs including the African Growth and Opportunity Act (AGOA). The GSP program is currently authorized through December 31, 2020.
Has the GSP program ever expired before being reauthorized? The GSP program has lapsed prior to its reauthorization in 10 of the 14 times it was extended. Congressional practice has been to extend the program retroactively from the original expiration date, so that importers are refunded (without interest) for the duties incurred during the lapse.