All the paragons essences are obtainable and even the others, the only one I don't know they are availabe are Hertz Locker and Conflict and Strife considering you can still rank in rated arenas and get loot from chest and even the rank 1 - 3 essences. I heard people they did Keystone Master in pre-patch (I finished before BFA) and I managed to buy the rank 4 essences in my mage in pre-patch because I did the achie before pre-patch. I don't know, it's so weird. At least I hope they keep it like this, at least to have something to work towards.
I got "The Ever-Rising Tide" rank 4 from Unshackled Supply this week so its still obtainable in pre-patch.
The pvp essence rank 4s are available on the vendor. I'm working at battlefield master. 12k to go -.-
Its a bug then, patch notes says not obtainable, report it as a bug. Benefits from bugs result is bans because that is called exploiting. This by definition is a bug.
I got an essence from both Unshackled and Rustbolt Paragon Caches druing the pre-patch already.
I pulled Purification Protocol r4 today, so that is definitely still in the game. So is Memory of Lucid Dreams r4, just completed that today on a character and it was properly rewarded.
as someone else also posted above I have also gotten the rank 4 worldvein essence "brilliant worldvein" on several characters just this last week during the prepatch.
I received Vellum of Illuminating Tides from an Ankoan paragon chest a few days ago. (Not one that was received before prepatch.) Not sure if that's a bug or intended.
Yesterday I got a Rank 4 essence from Ankoan, so I can confirm they can drop from the paragon chest
The Ever-Rising Tide still drops! My friend got it yesterday on her druid from the Ankoan Waveblade paragon chest. Same goes for the other essences from the same paragon chest.
I can confirm that I got R4 Unshackled and Mechagon reputation ones both during prepatch and got Azeroth's Champion Achievement today as a result.
I have the mission for rank 4 world vein, which I received last week on an alt. It completes in 9 hours (5% chance to fail).
WHY WHY WHY? WHY BLIZZ MAKING EVERYTHING UNOBTAINABLE?
Not sure if its a bug or not, but one of my alts that had completed Keystone Master its still able to buy the M+ rank 4 essences from the Thaumaturge.
I got r4 worldvein in prepatch.
Why rank 4 essences couldn't be obtainable anymore ? I mean the achievement, I understand, but why would they removed them altogether, that's just plain stupid.