I wish it had a happy ending (obvious spoilers)
Elizabeth should have just lived out her life in her universe with hero Booker.
I suppose now there can be a sequel!
Have you seen the post-credits scene? It's a little happier.
shareNo OP is right it's kinda a sad ending (yes I've seen the end credits).
It just shows the whole cycle starting up again, as nothing can change.
When the Elizabeth's drown young Booker, they prevent the future (Columbia etc.,.) from existing, which means the whole story never existed and thus young booker didn't drown.
What we see at the end is just the beginning of the whole thing.
OP is right Elizabeth should have cut her losses and went to Paris.
I interpreted it kinda differently... I got from it that since the cycle was broken (Booker's drowning) Comstock couldn't exist, so he couldn't come and offer to pay off Booker's debts in exchange for the girl. Thus Booker and Anna lived happily ever after...maybe.
But yes, with no more Columbia, all the adventures with Elizabeth couldn't have happened. That's kind of sad.
I kinda hoped that Booker and Anna lived happily ever after. But it would go against all the laws of the universe set forth in the game, and common sense.
Originally, before the start of the game events, Bookers life caused him to have a crisis of personality where in half of the time he stayed Booker DeWitt and the other half he turned into Comstock .
Elizabeth's plan to kill Booker at that choice would have prevented Elizabeth's very existence since she was born after that choice. The fact that we see a baby Elizabeth tells us her plan failed, and Booker didn't die.
Why didn't he did? Because when Elizabeth killed him at the end of the story she disappeared for existence as did Columbia. Meaning there was no Elizabeth anymore to go back and drown Booker. Thus the story progressed as before. Kinda Sad. There is no way Elizabeth can change things.
It wasn't a Jekyl and Hyde thing, Comstock only exists post-baptism, he never did before. Was Booker a lonely, miserable person; yes, but he didn't have dissociative personality disorder.
shareI think the Elizabeth we know escaped being snuffed out. They're playing fast and loose with multiverse so you can't really say what is and isn't possible based on 'their rules.' She is not Comstock, she is an omniscient being, probably on the level surpassing the Luteces.
Evidence:
1. If we accept that the first Elizabeth shown in the drowning scene is 'our' Elizabeth, this Elizabeth is not explicitly shown being snuffed out. It cuts to black before that. That ambiguity seems absolutely intentional.
2. It is possible that the first Elizabeth shown in the drowning scene is not 'our' Elizabeth (the one that says 'are you sure?' before opening the door). There is actually a bit of evidence that supports this. First, she does not have a pendant on. The 'are you sure' Elizabeth had a pendant, and had it on throughout the entire ending sequence prior to the drowning scene (including watching Booker rejecting baptism the first time). Second, Booker expresses confusion over her identity ('Wait, you're not.. who are you?' or something to that effect).
I do NOT think the lack of pendant in the drowning scene was simply developer oversight. I am a software developer, and work with 10 professional QA testers. These people are trained to catch the most obsure edge cases, and they do. Did you see the list of QA testers in the credits for Infinite? It was a mile long! The likelihood of that pendant being missing by oversight is extremely slim. If I as a developer not even connected to the project noticed this, you can bet your ass this is a known issue. So, even if the 'first Elizabeth' disappeared, we do not see the 'are you sure?' Elizabeth disappear.
In short, I think the game creators left a lot of wiggle room for the adventure to continue.