[tomtkp]

Originally Posted by SAOfreak

Considering author changed how he tell about the content of volume 11 in SAOP1, compared to what he said in SAO10, I think volume 11 might cover chapter 5+6 and very early part of chapter 7.

Spoiler:

before the introduction of a certain loli.
But your point Three is also highly possible, looking back in volume 9&10, author always opened the volume with POV of characters other than Kirito, so he might want to save chapter 6 for the opener of volume 12.

In that case, volume 11 cover should be the two girls introduced at the end of volume 10.

I don't think the author has changed what he said about the content of Volume 10 in Progressive 1 afterword.

Volume 11 afterword:

In the third volume of the <<Alicization series>>, Kirito and Eugeo will finally move to the core of Underworld. How the world is constructed, and who rules this world will be revealed…these should be all for future developments

Progressive 1 afterword:

The next is, of course, the fact that I'm still continuing the main arc of SAO. The 3rd part of the Alicization arc, which is volume 11, is planned to be published in December. Kirito and Eugeo will be approaching more and more secrets of Underworld......probably

The author was basically saying the same thing, Kirito and Eugeo approaching the secrets of Underworld.

But I see you may have a point that my third scenerio has higher chance after reading the above quotes.