Back when 5.2 was still fairly fresh, one of the leading guesses as to Venat's present situation was that, like Elidibus, she somehow survived being sacrificed to summon her respective primal and went on to reincarnate into Minfilia (and later Ryne). Of course, the matter of Ryne's soul is... hardly cut and dry, to say the least. And with the 5.3 revelation that Elidibus has been a primal ever since he popped back out of Zodiark, it's hard to believe that the same can be true of Venat anymore.

Minfilia probably wasn't a primal, after all. Unless she was. That'd be one hell of a loop to be thrown for, wouldn't it? So I think, whatever happened to Venat post-sacrifice, is all still up in the air.