Next JTR event?

Hero’s Journeys
Similar to Legendaries and Mythics, we have a concept of a New and Legacy Hero’s Journey.
The first two runs of a Hero’s Journey we consider New and will give at least a week’s notice before their launch.
Unlike a Legendary or Mythic, when a Hero’s Journey becomes a Legacy event we will not necessarily post it to the Event Calendar at the beginning of the month. However, the intention is that Hero’s Journey events will return roughly every three to four months after they become a Legacy event and that we will give at least a week’s notice before they return to the game. When we announce the return of the Hero’s Journey event, we will post it on the Event Calendar on the forums.

From the devs themselves.

So unless tvf and kyno think that trust the devs will follow their own officially stated schedule is guessing (many on those forums will argue it is), there is no guessing. JTR will be back in september-october.