What makes you say that? They were left ambiguous in the novel because it was about The Last Jedi. This series is about Thrawn.
I also just want them to PLEASE give me an answer. I just need one, answer. The Yuuzhan Vong are something which we've already seen in the legends continuity, so I'm up for something new. If they're not going to tell us what's in the Unknown Regions, they could at least give us a hint! That's all I need. What is the nature of those things from the unknown regions? And it'd be amazing if they showed us what Snoke's earlier days in the unknown regions were like.
That sounds like something I want to know more about, though...
I am talking about the Thrawn novelization exclusively. It ambiguously references the Unknown Region's threats, just like the comic adaptation has.
Here are pertinent excerpts from the novel:
Whatever said threats are, they're more evil and dangerous to ALL living beings than even the Empire was... And that was according to Thrawn after he'd been part of the Imperial hierarchy for a number of years(he was an Admiral at the time), and also after he'd gained working knowledge of the Death Star and its capabilities. So yeah, the threats he is aware of in the Unknown Regions must be uber AF if he STILL considered them more dangerous than the Empire.
That said, there is not a doubt in my mind that the Vong will eventually be revealed as one of these canon threats(likely the most evil/dangerous threat of all)... And they will be ridiculously OP when they finally appear, me thinks.
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"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
Well, that's...kind of something new? I'll try and be happy about it when it comes out, but that's about as much of a compliment as I can give it. Sorry master Yoda.