It could be the titans in general too though they are dead I believe? The Old Gods long standing adversary has always been the Pantheon. Azeroth is the obvious choice but I dunno, the Old Gods have been fighting the Titans, the titanic watchers, dragonflight, and all of the races made from flesh of curse too compared Azeroth who felt to be "quiet". The mortals fought on her behalf unknowingly. Magni dmust have too until the ritual changed him and allowed communication. With the Aspect of Earth, we don't have any direct accordance of them speaking to Azeroth I do say but I don't recall many good ones being around to really ask and well Deathwing was nuts and beyond asking.
I've toyed with the idea that the 5 lights aren't the pillars of creation, there were 5 Aspects. They are all mortal now, Deathwing and Ysera are dead for starters. And with Deathwing it feels to me now like they purposely picked Deathwing to mess up considering Nozdormu knows he will go crazy in the future (and not sure if the Infinite Dragonlight bringing the Hour of Twilight is still canon), therefore would be an easier target to corrupt quicker. It's just Neltharion is the aspect of Earth which now that Azeroth is precious seems quite coincidence. Or is it they are planning to mess them all up? 2 out of 5 are already gone, 3 will be corrupted and may also have to be killed by us to rid his threat to Azeroth. That leaves Alexstraza and Kalec. Who we have been dealing with too.
That being said, if the dragonflight are the suggested lights then this would tie in with Odyn being the Lord of Ravens. The quote is about the 5 lights but before that refers them as to 5 keys. The lord of ravens whisper tells of turning the key. Odyn detested the idea of the Dragonflights and why he removed himself to Broken Shore.
All in all from some of these shared ideas on these whispers, these whispers seem to come to fruit quite quickly overall if this franchise is set to last a while.
Just to say Eyir is also a titanic watcher, it's stated in the Dungeon Journal of Hyrja's background entry. Obviously they could conflict on some things, she evidently followed Odyn though there's virtually not a lot about her or Odyn at this time.