Hmm, I remember him commenting on us undoing his work with Ysayle, but I also recall him mentioning having to suffer Lahabreas company in the same breath, which made it sound more like they worked together on it, with Lahabrea being in charge and thus (in my mind) ultimately responsible... I'd hope Nabriales was simply claiming more credit than he was due, just because it would make me dislike him all the more, but I suppose we have Lahabrea + Nabriales for Shiva, and Lahabrea + Igeyorhm for Thordan... Hopefully an Echo cutscene in Snowcloak (Hard) can shed some light on that...
So far the Echo has been fairly rooted in simply breaking down the barriers (exclusively between souls?) for various effect, though... You can see someone or somethings history, or understand their meaning without understanding their language, or you can fuse souls or gain immortality by hijacking other living things... I guess we can still gain some future reading off that, or rather, we can break down the barriers between worlds and look at an alternate timeline...
Still seems far fetched to me, though it could make for an interesting plot detail (though equally, it could make for a terrible one...), but really... If Alisaie has the gift of foresight through the Echo, she sure as hell isn't displaying it... If I had that gift and Derplander sniffed me out, I wouldn't have been shocked, I'd have known he was about to find me and I'd have known Thancred was about to jump to my rescue... I really don't think she has any such gift, I think the defenses Urianger put in place after the last attack on the Waking Sands gave Alisaie a heads up on what was about to go down and she just sent aid... It makes sense the Crystal Braves would want to lock down the Waking Sands for the same reason they'd take the Rising Stones, and as the brother of their commander, I imagine Alisaie would question what they're doing there and why Alphinaud told her nothing about it enough to connect the dots and send help...
Actually, scrap that, now that I think about it, didn't Tataru arrive there and warn them before heading off to Coerthas? She was attacked and took a boat from Limsa to Vesper Bay, so yeah... That's how Alisaie knew the Crystal Braves were turning... Tataru and Yugiri arrived and warned them while it was too late for us...