The Lost Allagan tank set was revealed in August 2016 and was implemented into the game in July 2017 so it could be quite a while...

On the other hand, the healer design was announced in April 2017 and was put into the game in October of the same year, but considering the timeframe of the new ones (announced at the start of patch 4.4) is closer to the tank's (end of patch 3.3) I think it's safe to say we'll have to wait until 5.0 to wear them ourselves.