3- Any apparent foreshadowing by Oda?
Now there is no clear indication that Nami will inherit the fruit, but I feel Oda has given some vague clues about Nami using the Soru Soru no Mi to her advantage:
1- Nami controlling Big Mom’s Homies. Now as far as we are seen, the only person to control the Homies apart from Big Mom was Nami. She even made these Homies attack Big Mom’s own children like Cracker and Brulee. Yes, she used Big Mom’s Vivre Card to do it. But is this some kind of foreshadowing telling us that Nami will have Homies of her own in the future.
2- Big Mom using weather based powers. Now we all know that Nami has weather based powers. As these abilities get stronger, she gets stronger. Now in One Piece so far, among all the characters introduced, the person with strongest ability to manipulate weather is Big Mom. So combining both the statements I can say that Nami can become her strongest only if she can use the weather manipulation abilities of Big Mom.
The fact that during the escape from Totto Land, Zeus was captured by the Straw Hat Pirates and forced to become Nami’s servant. He lived inside her Clima-Tact until he was reclaimed by Big Mom in Wano Country.
I still think that Zeus will be Nami’s go to weapon towards the end of Wano Arc.
4- How strong will Nami be after she gets the Soru Soru no Mi devil fruit?
The biggest plus of this ability will be in Naval Battles because she can literally turn the tides to favor the Straw Hats. Remember when Roger faced Shiki, the bizarre weather conditions turned the favor of the battle between them from Shiki to Roger as the weather sank quite a bit of Shiki’s ships.
In 1v1 battles she can use and create homies to fight for her. If she beats people by scaring them, she can steal souls, there by making her more powerful and have more homies for her future battles.
*Theory by Ashura the demon