China Southern Airlines (CZ, Guangzhou) has announced that by 2021, it will have retired its remaining B737-300, B757-200, and B777-200s as part of its 13th Five-year Plan. Once gone, they will be replaced with A320neo, B737 MAX, and B787-9s among other types.
According to the ch-aviation fleets database, China Southern currently operates three B737-300s, ten B757-200s, and four B777-200s.