It's more than obvious that Luffy won't end up as feral monkey. He won't be able to fulfill his dream if he lose to his inner animal that came with his df.
I would like to see that but I think this desperate situation just triggered full awakening and to get out of it successfully Luffy need to keep his humanity. Though I really like the idea that all of this is some kind of hallucination that Luffy have right now.
Thing is for me, the last time we saw Luffy, he was begging his heart to keep going because he needed to stay if the fight. And then, I belive he went. "Hmm?" indicating that something happened.
If the fruit is taking over, it's probably just doing Luffy a favor. It's doing what Luffy begged it to do. Possibly. In this interpretation.
As fort he monkey form, I feel like given that Luffy can turn into a genie, Luffy can probably turn into multiple animals if he needs to. It's monkey right now, probably due to how many attacks are associated to primates, his name, and also maybe an homage to Sun Wukong/dragon ball, so and so.
But yeah, after seeing Luffy as a genie, he can do anything.
I do not believe the primates are associated to Nika, deific symbology wise. I think the form only exists because of Luffy's nature.