I don't think the Dark Elves are interested in Gfay right now. I think they have their eyes set on Freeport. Since Freeport is already split they would have a relativly easy time of controlling the city. There is no chance to control Felwithe or Kelethin as they would be right in the other races backyard.
There are Dark Elf Instigators in Crushbone as I speak. I think their plan is to convince the Orcs to keep the Light elves busy so that they will not interfere with their siege of Freeport. The only race with an army large and well organized enough to repel the Dark Elf invasion of Freeport is the High elves. By convincing the Orcs to finally make good on their promise to "Burn Kelethin to the Ground" the Dark elves force the High elves into protection of their close kin the Wood Elves. The Dark elves know that the Orcs are not strong or orginized enough to win a war against the light elves but that is not important to the DEs only time is.
It also looks as if the trolls are poised to take back Gukta. Based on the priest summoning the Troll in Innothole the Dark Elves will also look to occupy the Noble Guktans with repelling their own invasion and in the process get the city of Neriak back to themselves as well.
The Dark Elves are not strong enough to wage a straight out war against the lighter races. The light races would normally not let them control such an important tradecity as Freeport. But with manipulation and trickery they stand a chance of befuddling the light races long enough to Blitz Freeport and take control before anyone has the time or resources to react.
All of this is of course just my own opinion, we wont know until it finally unfolds