There isn't a lot of information out there yet, but it was announced that PR16 will premiere earlier than usual this year, on Thursday August 17th.

It could be that they are trying to time things better with September Fashion Week, so that they don't have to show decoy shows for the entire cast, or risk major spoilers coming out as the season is just beginning.

I don't usually use links to, but this article does a good job of gathering lots of stray bits of information on social media from the past couple of weeks:

Heidi Klum Dishes On ‘Project Runway’ Season 16 Filming: Says Designers ‘Not Happy’ With Plus-Sized Twist

More plus-size models this season! And the designers aren't happy! I'm SHOCKED!