Maybe a mistake, but I think Brad has everything story planned out for this years in advance. Hence the book.
Which is a shame, and limits creative control and ability to respond to feedback. An expansion set that really shakes things up, adds some traditional fantasy races (with an Elemental twist) and revamps the Fallen (keep a few, make them very unique from the humans and each other) is really needed.
A second cataclysm that sunders time and space and merges Elemental with another plane could do the trick. (and due to wibbly-wobbly timey-wimey doesn't necessarily negate Brad's book, it's just an alternate universe where Nero didn't kill Kirk's dad with a space squid... ermm...)
Something like one of the Fallen Empires (Resoln acting on something their oracles had planned for centuries?) attempting to summon back the Titans, resulting in the world the Titans are from being sundered and meshed with Elemental itself. Many races that the Titans had fought and nearly conquered (Elves, Dwarves) coming back to the forefront and fighting with men and the surviving Fallen. The east and west similarly shattered as entire landmasses are warped and shifted between the planes. Time itself also being broken momentarily with causality shattered. Empires the Titans annihilated restored on the broken continents in the blink of an eye, etc.
The net result- carte blanche to rewrite backstory as needed, put in some traditional races and give them new back stories, and keep the kingdoms and empires that people like the best and make them a bit more unique gameplay wise. (Say Tarth and New Pariden survive and play differently as the "Barbarian" and "High Men" archetype factions)
Channelers from what were two separate worlds have to cope with the fact that the laws of magic are still settling down from this terrible event, and there could even be differences in how magic plays out on parts of the landscape due to the residual energies of each world interacting.