Despite the similarities of their appearances (and, I suppose, actions, in that they both <3 Cable and would follow him anywhere), I don't see how there's any way that little Hope could grow up to be big Hope. Swiercyznski would have to pull off something absolutely amazing to make that work.
If this kid is indeed supposed to do something amazing as part of being some messiah, or even some possible messiah, it's impossible (from what we've seen) for her to do that from New Liberty (which probably won't be revisited). The only flaw here is that we obviously went to New Liberty for a reason, and the older Hope was obviously introduced for a reason, and that can't be discounted.
Even if Cable takes the path of not wanting the kid to be confined to destiny, finds some way to travel back in time, and decides to leave her in New Liberty so she can be protected - at this point, that means putting her there with the knowledge that, when the loop completes, his younger self is going to meet her older self, live with her, raise her as a kid, and eventually lead her to her death. And seriously, that's a pretty prick thing to do.
