Elidibus is the only one I'm not certain is in the Lifestream, because we see his aether (and the aether of all the Memorial Stones) be absorbed by the Crystal Tower and the Crystal Tower itself never gets destroyed to release the aether in it. The Tower can safely hold
so much aether indefinitely that I can't see Elidibus breaking out either. The other thing that makes Elidibus different is that he's part of Zoidark, Zoidark's heart to be exact. I don't know if we really
can return Eldiibus to the Lifestream until Zodiark himself is killed. So the Crystal Tower might just be a stop-gap solution until we're ready to defeat Zoidark for good.
Emet-Selch is weird, but not because of how we defeat him. We still flood him with all the Light Aether we picked up from the Lightwardens and also a lot of the Scions' donated aether. We just don't try containing him in an Auracite first like we do the other Ascians. Emet-Selch is weird because his own aether affinity is the aether of the Lifestream. (
Check out his short-story from last year's Rising for more details.) He was quite literally the best Ancient at manipulating it. In fact, it's why he had the office of Emet-Selch to begin with. So when we killed Emet-Selch for real, we essentially sent him to the place his aether was already very, very skilled at manipulating. Which... could be interesting going forward. Or rather, has been interesting already most likely given who shows up when we use our Azem power to bring in someone who can pull us out of the Rift.
The Lifestream is where Hydaelyn also is. And we haven't been able to have contact with her since 3.4 when Minfillia left to save the 1st Shard. So it's high time we had a chat with Hydaelyn about all this... but how to get to her? I find it... very convenient... that someone who was really good at manipulating the Lifestream in life is now actually in the Lifestream. And we've already somehow called upon them once...