What LGS said.
Cedric doesn't seem to know exactly what will be at MAGIC '17 in terms of Shenmue III just yet. If it was the re-reveal I don't think he'd give that answer; because Shenmue III is a guaranteed ticket-seller and hyping it up as the first proper look at the game would be beneficial to him and MAGIC.
What we know for sure
is that there are no plans for a big update before December. That doesn't guarantee a December reveal by any means, but when I asked:
Is it safe to say we may get something big in December, or is there no plan for that either?
His response was:
I am not a spoiler ! ;)
He's playing coy, but given he directly
said they have no plans for a big update before December, I don't think he'd dodge my question like that if there was nothing in the pipeline.
Now, as for PSX, it's just educated guesswork that it'll be there based on Yu being in LA the same month, and the obvious Sony connection.
It could appear at The Game Awards (though I doubt it, PSX is a better fan-oriented venue), or just a big Kickstarter update around Christmas, but given what the Japan dinner backers have said about what they saw (and it being old material at that), a big, public re-reveal seems like an imminent inevitability rather than something we're just dreaming about.