“The ending is reality.
Cobb seeks Saito in Limbo where they remind each other the world is not real, Saito’s gun appears, and the sedative had worn off.
How do we know, because when they come out of Limbo, everyone is wide awake and alert, (key word being “alert”).
It seems pretty clear cut to me.
What the kids look like in his memories and dreams:
What the kids look like in the end:
Now by the photos (and casting), we can see that the children are much older in the end. Notice the clothing… the dress is the same color, but in the end she is wearing a shirt underneath it. And it’s now sleeveless. As if it’s the same outfit only tailored to fit because she has grown out of it.
Also we hear the top begin to wobble which means it is about to fall. A wobbling top always falls.
End of story. The story about a man who is imperfect, who loved deeply, who lost profoundly, who found his way back home…”