Who do you thinks gonna end up abstracting?
Well this is a bit of an old question buuuuut:
Hm.... honestly, I'm not sure! There's a case that could be made for literally any of them abstracting, especially with the episodes all slowly revealing more and more canon things about each character's mental state. Surprisingly (or unsurprisingly?) I think the least likely ones to abstract would be Pomni, Zooble, and Kinger mostly. Kinger because he's just so crazy most of the time that- well- he can't exactly give into the abstraction, while Pomni and Zooble just seem to be doing the 'best' mentally, even if they do have their own mental hang ups. It does make some sense, if you consider the fact that those two have been there the least amount of time compared to everyone else.
But back to the previous question- that leavesss Ragatha, Jax, and Gangle to possibly abstract. If we're going by just the players, I would guess that Ragatha would be the first of those three to fully give into the abstraction. Gangle is obviously not doing the best, but she has more of a support system to fall back on than either Jax or Ragatha do. Jax, meanwhile, has somewhat fallen into a mindset that he doesn't necessarily care what the others think of him, and that he can do whatever he wants in the digital world without consequence. As long as nothing breaks this attitude of his- which I could see happening, but thus far has only sort of happened in this latest Spudsy's episode- I think he'd be fine. Ragatha, meanwhile, is liked in the circus. She, however, hates upsetting people, and does not have much of a real support system to fall back onto. She masks most of her opinions on things, and would probably mask when she's feeling genuinely upset about bigger things. Her rambling in the very first episode also makes me wonder how close to her 'breaking point' she really is.
Here's a bit of a plot twist, though- I actually think Caine is more likely to crash out or get close to it BEFORE any of the main cast abstract. The third episode had him slowly start bugging out as Zooble told him off about his adventures, and then right after Gangle left him in his office in the most recent episode he began to bug out as well. Goose has also hinted that there will be some 'Caine angst' during the show as well, which leads me to believe that his glitching and the breaking down of the system will only get worse with the episodes to come. Whether this is a good thing for the players- where he breaks down and their minds are maaagically taken back to their bodies at the cost of his life- or a bad thing for them- where he breaks down, the system breaks down, and then they either end up dead or forever trapped in this endless Void with nothing to distract them from the nothingness of this world- I am unsure. I could see it going either way.
TLDR: So far I could see Ragatha abstracting first of the main cast, but Caine might get close to or ACTUALLY break down before that.
I'm sure everything I've said up to this point will be proven WRONG in the future, but for now those are my thoughts! Apologies this got super long, I kind of just let myself type my stream of consciousness here haha. Thank you for the question!