I'm impressed that the core books doesn't show a direct reference to the Storm of Chaos events of the Second Edition. The obvious path was to set the Third Edition after the attack of Archaon, but there is only one or another reference about "the last Chaos attack, the greatest one since the time of Magnus" (I actually thought that the Storm of Chaos was worse and bigger than the Great Chaos War).
So, what happened to Archaon? Is he still hiding in the Middle Mountains? Is the Third Edition going to simply pass through it, without greater reference?