The thing with the world core is just going there doesn't necessarily mean anything. We know Azeroth has to hatch specifically at some point, going to the world core before that doesn't take away from "Azeroth hatches out and grabs the sword"
They're not going to drop the one guiding thing we've had between every zone in this game. Even going out to the Undermine was because the Worldsoul specifically sent a message to Orweyna, and 'where do those weird haranir guys come from' is still a hanging plot thread that's far easier to tug on than 'oops we're off to space to chase Bob mcIrrelevantToTheStory rather than deal with Xal'atath", especially when its somewhere. Just change 'whatever Rootlands originally was' to 'the sleeping world core is here and Xal'atath's trying to flood it with black blood, the haranir are trying to stop her but are woefully unprepared for this', blam, instant end patch
K'aresh makes zero sense as the next patch. It isn't a threat, it has nothing to do with the World Soul, it has nothing to do with Beledar, it has nothing to do with Azeroth. Neat place to visit one day, sure, but its irrelevant to the whole black blood corruption problems or the stuff we've been focusing on to face the Void. We have, genuinely, no reason to go there at all.
Do remember, the only datamined thing was the icons saying 'etherealraid', and you don't need K'aresh for an Ethereal raid as Outland showed us with its Ethereal dungeons. Plus, for all we know, the original etherealraid was a victim or the storyline changes and got shoved into Midnight itself.