Is this just speculation, or do we have concrete reason to believe this? I understood the original intent was to split AMoL into three books of roughly equal length.

In any case, although your points are well made, I can't see the Egwene-Tuon alliance and their subsequent confrontation with Rand happening at the peak of TG, at which point Rand would presumably be in the front line rather than negotiating behind the scenes. Still, we shall see.