Who do you think he would end up with? People might joke that Luffy has his "harem" of princess, but the only woman I recall actually being romantically interested in him, aside from hints with Alvida, was Hancock. And if you think that he won't produce kids, you are on crack. No way Oda would get away without at least some sequel bait.
Her endgame arc similarly to Luffys has to involve a kid in some way. Luffy is going to have a kid at the end of OP. Even without the reasons you say, every important pirate in OP has a kid of some kind other then Blackbeard and Mihawk.
Nami’s whole plotline and symbolism back through OP and East Blue is so aligned to the endgame when you look back at the forshadowing and information we know now.
Nami is also the main female of this era. And she has a lot of thematic parallels from what we can tell to Imu
She and Luffy are also thematically opposites but Oda makes it clear Luffy needs that in order to thrive on the sea and in life