According to Eiichiro Oda this series takes place 15 years after the series finaly.
Monkey D. Laffy (Luffy's son)
Nico BlueJay (Nico Robins daughter)
U-popp (Usopps Grampa)
Zero (Zoro's son)
Johnny Johnny Cutter (Choppers son)
Other things confirmed
Chiller Stump (New Thriller Bark)
World Thugs (Poor Versions of World Nobles)
Not much is known about Two Piece for now.