I don't know how much of that is actually true, because I heard Henning and Richmond (the game director) were having trouble with Uncharted 4, and the two heads at Naughty Dog not being too pleased with how it was shaping up. Which apparently prompted them to put Druckmann and Straley on the project after the major succes of The Last of Us. And it appears Straley really didn't want to, due to being overworked, which it seems is what made him leave Naughty Dog not too long after.Would have to guess that’s a big part of why Hennig left. Druckmann had more pull for whatever reason, for better or worse. Just read he was named Co-President now too.
Some trouble definitely went down over there, but I'm not sure which side to fall on until I hear some actual claims by Henning.