This is the obvious, and only, conclusion. Luffy and Nami actually match each other (personality, dreams, etc), they actually know each other and have a deep relationship, and would be equal in it. That is opposite for Hancock, who has none of the things that Nami does and would only be a doormat with Luffy.
Luffy ending with Nami and Nami ending with Luffy is the only outcome that makes sense for either one of them, it’s either each other (if Oda goes that route), or no one.