Not that access SG via T'A'R or some such isn't important, but two things jumped out at me immediately upon reading this.

1) "His blood on the rocks of SG"

Well, we've all assumed that would happen AT SG, but now, it may not. Of course, "his blood" may not be literal, and could refer to his bloodline (Elayne's babies, Galad, or even Luc), but the blood being shed to free the world from the DO could happen in Caemlyn.

2) Taim's status.

Feed the Taim/Moridin fires somewhat more, doesn't it? I mean, bringing SG rock into the BT for just some 3rd Age DF seems a bit extravagant, doesn't it? Maybe there is some property to it that makes it necessary, perhaps its a part of the "key" to the dreamspike now in use? But still, the fact that Moridin's palace is also made of Black seems to jump right out at me.

Of course, we now know that the term "palace" was used a bit loosely. But still, I think Taim must either be Moridin, or his proxy.