Looks like this will be a DLC for Uncharted 4, featuring Chloe Frazier from 2 and 3 (But who was absent for 4 apart from a small mention and multiplayed mode) and Nadine, the mercenary from 4. It's a bit unclear what the plot is, or if it really is connected to the other games apart from the two ladies:
http://www.polygon.com/2016/12/3/138...on-naughty-dog