Elizabeth's necklace changes to the opposite?

Solution 1:

That's up to you. Honestly, I got the feeling that the entire game was mocking the idea of meaningful choice in the context of a game. All the little experiments the Luteces conduct with you are just micro versions of everything that's happening on a larger scale. You've played the game, you know how it will always end.

Did you throw the ball at the couple, or the man on the stage? Doesn't matter, it continues on no matter what you chose.

Switching the pendant on you, in front of your very eyes could mean that Elizabeth is collapsing into a singular version of herself, a coalescence of the alternative versions of herself into a singular entity across time. It could mean that "your" Elizabeth is gone, because all Elizabeth's are gone, collapsed into a singular "oversoul" that has broken down the barriers between her own minds across timelines.

But there is little actual evidence. Things got really 2001 A Space Odyssey near the end. Endings like that tend to leave a lot up to the imagination, and that's not a bad thing.

In music, the silence between notes is just as important as what notes you play. What you choose to fill that silence with is up to you, and how the piece makes you feel.