i was listening to wide awake by katy perry and realised that isayama must have told her the ending in 2012, it's pretty obvious. listen to this:

I'm wide awake
Yeah, I was in the dark

this refers to eren waking up from his dream and getting on with the apocalypse

And now it's clear to me
That everything you see
Ain't always what it seems

this is referring to when eren got to see the memories and had to interpret them

I wish I knew then
What I know now
Wouldn't dive in
Wouldn't bow down

this is referring to when eren didn't know the memories yet so he was off doing shit

Gravity hurts
You made it so sweet
Till I woke up on
On the concrete

this is referring to that time eren couldn't make the odm gear work and fell on the floor, clearly he's still embarrassed because everyone was watching, especially reiner

Falling from cloud nine
Crashing from the high

this is a reference to when eren was having a party above the clouds where only armeen was invited but he was too busy chatting up annie so eren starts crashing everything beneath him

Yeah, I am born again
Out of the lion's den

this is ymir singing for when she's reborn as eren's child

Thunder rumbling
Castles crumbling
I am trying to hold on
God knows that I tried
Seeing the bright side
But I'm not blind anymore
I'm wide awake

This speaks for itself since Katy Perry mentions the rumbling and everything being destroyed, and that eren tried but there was no solution

Also watch the video, grown up Katy Perry meets with little Katy Petty, I think Revo wrote the lyrics of this song