Looks like the DLC will be launching soon given this posting by Blizzard. The class is also temporarily offline for play on the beta test (I was going to try and resume leveling again but found it was unavailable). I also missed the server slam test they had from May 30th-June 2nd where they turned on buffs for blood shards and XP.
Stress tests usually are performed a few weeks before projected launch. Heroes of the Storm has this cross promotion happening with Diablo III from June 13-26 (also announced on the 5th). The trailer for the class was released on June 1st; all of this ramping up is a sign that marketing already has a tentative schedule pointing to a release by the end of this month. The closed beta will likely receive one final patch with the tuning passes they plan to go live with (unless any egregious issues are found before then).
The next announcement will likely be next week with the pricing and actual release date (my guess on that is around $24.99).
I won’t be purchasing it though because while I have been finding the class fun to play, nothing has changed regarding the reasons why I stopped playing the game (nothing in this beta test gave me the urge to resume playing my main account again). If things had changed, I would’ve been playing this beta non-stop. That is how detached I have become as usually once I decide to stop playing something, I rarely look backwards (as more often than not, changes are not made for those issues that caused me to stop playing in the first place).
I do expect they will do extremely well with this DLC though especially if it is priced at that $25 point (and if they come in below that at say $19.99, then they will capture many who are sitting on the fence).