I mean, it's just speculation on my behalf, but I believe the 1.3.5 update is pretty close.
One of the things we learned from the cancelling of Terraria: Otherworld is that Re-Logic will no longer release spoilers and tease and, most notabley, hype people up about their new projects, until they can be certain that they can keep up the spoilers and the hype until the release of said projects.
It wouldn't be a stretch to apply this logic to Terraria's future updates, in this case, 1.3.6. After all it would be counterproductive to hype people up about the update if they have no idea if they can keep up with the spoilers and the hype until release.
And we can see this happen in action : the development of 1.3.6 began quite a moment before Terraria: Otherworld was officially cancelled, and probably internally too, and we got quite early spoilers of 1.3.6 as well ; I assume they were before Re-Logic had the wake up call of the dangers of hype with Terraria: Otherworld.
Then, the spoilers kind of slowed down, a lot, I assume it is because Re-Logic decided to not hype people up anymore than they already are about 1.3.6, until they can be certain that they can keep up with the spoilers and the hype until release.
Then, quite recently, we see an increase of spoilers, quite a drastic one at that. And so it leads me to believe that 1.3.6's release is close enough to Re-Logic's point of view that they can keep up the spoilers, and the hype, until release.
That does not necessarily mean that they have a release date set in stone, but I do believe that they know that they are getting quite close indeed to the eventual release of 1.3.6.
So I'm hyped beyond reason !