The Proving Grounds events are on an indefinite hiatus. We appreciate that there are a set of fans who really enjoy them (we do, too!), however as we shifted over to the expansion release schedule that has taken the entirety of our focus.
Any future updates regarding the Proving Grounds will come in the form of an official news item; I would warn against trying to glean information from any updates picked up on a testing server, like from Hoboleaks, without any official announcements.
I know it’s not the answer you were hoping for, but I appreciate your understanding.