Thank you, D Sqn.
I can't see where Thomas Coupling got that gem from, but it isn't something I've seen elsewhere; he may have inside information, who knows. There was no expectation to publish before the Summer, but that was the AAIB estimate before they had reallt started the in-depth stuff. how the investigation has progressed since then would not be in the public domain; they wouldn't raise false hopes by suggesting an earlier date until they're ready to go.
Despite that, it's entirely possible that they're drafting now, but untill we see otherwise, I'm expecting the original date. Earlier, of course, would be good if they've finished.