Anything is possible but I don't think Nami and Hancock will fight just because of Luffy.
If she joined cross guild , then she may got another reason to fight Nami. That's much better.
Jormungandr is sea serpent. Not just snake...
More likely red line represents Jormungandr
Something I have talk about before -
How Jormungandr is drawn , looks similar to Luffy drawing of Nami.
Nami is from Sweden. Sweden = Viking = Elbaf.
(Sweden connection is about ancient city Birka. Maybe Elbaf has another way to reach Sky island. They did talk about easy way to reach Sky island)
Jormungandr is enemy of Thor. Thunder connection with Nami.
Jormungandr disguised herself as Cat (Cat burglar Nami ).
"Ever since Jormungandr was a little child who could do no harm to the world, he was banished into the deep ocean in Midgard. The land of Midgard was surrounded by a vast ocean. And gods cursed Jormungand to forever stay under the vast ocean"
Nami was found as lost child by Bellemere.
Big Mom past and Nami past is similar but opposite.
Big Mom was banished to Elbaf.
Was Nami banished from Elbaf.
The first time Jormungandr emerged from the waves(Nami) was his first encounter with Thor.