It's another one of those ideas/thoughts that don't let me sleep at night untill I post them.
The new update chain is called "Return of Them" which means They will somehow appear in the game.
So I thought:
After defeating the Fuealweaver the whole underground shakes as Gateway explodes. Later you find out that one of the pillars in Ancient Guardian's liar has fallen over and created a bridge. That bridge leads to a forgetten, more darker and creepy part of the ruins.
When some terrible creatures are killing your kind some people will start to praise them in hopes of being spared.
In that new area you find remains of the cult of Them. Churches, sacrefice altars etc, etc.
In one of those cult churches you actually find some ancients praising a statue/idol of Them. They're alive but are only a shell of what they one were. Coming closer to them a text appears above their heads but in their language. You cannot interact with them, only examine. You can however hammer the idol.
After doing so the Ancients let out a terrible screech and start deforming- their bodies twisting and turning and snapping. Their mouths gaping open, eyes going black, nightmare fuel starts flowing from them. After that horror of a sight all that's left are Ancient Thulecite Statues showing those cultists in their agony.
And ofc breaking the idol would put you on a timer for a boss fight.