In the lead-up to season seven of "Once Upon a Time," it was clearly stated that the Regina of season seven would be OUR Regina, and not a doppleganger.
No such assurance was given for Hook, and with good reason. In the second episode of the season, we learned that Roger the Police Detective is not OUR Killian Jones, but rather the Wish Hook from last season. Yep, fat, drunk, gray-haired Hook, magically slimmed up and reformed (gosh, Hook always gets the easiest reformation stories) and with a quest for a missing daughter.
The weird thing is that we have no idea how old this daughter could be. In the wish universe, all sorts of histories were magically inserted, even though real people didn't live through those years. So Hook's daughter could be a young teen (though not as young as Lucy), or, let's face it, an old lady. (Because Hook's backstory is just so full of magical youth things even before the Stepmother's rejuvenating spell.)
Odds are high that his daughter is Alice, largely because she 'seems' like she could be the right age, and, of course, the chessman. (Chess sets being highly iconic imagery for Alice). We know next to nothing about this new Alice so it's convenient to pin her to this backstory. Since Alice is traditionally a world-jumper, it would make sense that she and her dad hopped over to this universe (and who knows how many others).
Here's the thing, in order for Hook's daughter to be a grown-up, she needs to also be from the Wish universe. The Wish universe didn't exist until season six, which seems to be separated from the 'now' of season 7 by about 15 years, so whatever backstories/people magically came into being at that point, going forward anything new happening must occur in real time. There just plain isn't time for Hook to have jumped around universes and fathered a daughter old enough to eventually marry Henry.
And even if you argue that maybe Henry had magical youth stuff going on, in the Flashback where he meets Cinderella he clearly is not THAT much older, given that Emma and Real!Hook haven't aged visibly.
Bleh. This gets confusing fast. Anyhow, I'm predicting that Cinderella cannot feasibly be Hook's daughter, but since OUAT doesn't care about facts and logic and loves for everyone to be connected, she just MAY be anyhow.
Regardless of timelines, I am actually quite happy with this Hook switcheroo. It preserves the happy ending that Emma and Killian worked so hard for, while allowing there still to be a Hook on the show who is searching for his own happy ending.
On a slightly different note, I wish they'd saved Emma's appearance for later in the season. She didn't really do much in this episode, and the story would have worked just fine without her in it. I'd rather have seen her later on in a brief appearance with her new baby. Here's hoping that we WILL get that as a surprise later on. Fingers crossed!
I'm really loving older Henry. Hook & Rumple are the awesome cop duo I hoped they'd be. Cinderella is...well, I'm still waiting for her to grow on me.