If "The Shadow of Odyssey" doesn't deal with an invasion from the Void (the Shadowmen's home plane), what else can we guess from the name? The title is fairly ambivalent. Is there something called Odyssey that casts a Shadow? Is there a Shadow from a place called Odyssey? Is it metaphorical -- could the appearance of Odyssey bring a darkness to the world?
Previous EQ2 expansions have always talked of places -- the Desert of Flames; the Kingdom of Sky; the Echoes of Faydwer; the Rise of Kunark. If they follow this same trend, then, Odyssey is a place. It is unlikely that it is a Shadowman place. It could be; we just don't know yet. Adventuring in the Void would be a truly unique experience.
There's no reason to go to another plane of existence for Odyssey... not when we have the whole continent of Odus still unfound. Odyssey, Odus... could the similarity of the names be just a coincidence? Five hundred years in EQ2's past, Erudites were fairly normal looking people. In EQ2's present, Erudites have evolved into something quite different indeed. Gray, almost metallic looking skin; colored tattoos on their bodies that seem to pulse with an arcane illumination. It is difficult to believe that a race so attuned to the threads of magic that connect together the universe would have been unaware of what was happening to Luclin, a moon surrounded by and infused with magic. They would have protected their home somehow.
Perhaps they gathered together their most powerful wizards and, using the power that had once torn from the ground an entire Kerran village and the land for kilometers below it and transported it to Luclin, pulled the continent from the land and took it to safety when the moon began to split and their cousins who had followed Quellious' call to travel to Qeynos had gone.
Freed from Norrath, Odus would become Odyssey; and in its journeys, would cast a very large shadow indeed. Now that the Age of Shattering is long over and the world of Norrath is at relative peace, they have returned. The Erudites we see around are exiles, waiting for the day when Quellious calls them home again.