Naruto can regrow other peoples eyes, and stop people from dying, so i'm wondering why he can't regrow an arm here.
I'm thinking once his chakra comes back, he'll be fine.
Granted, the movie not yet showing Sasuke's arm makes me wonder if he chooses to keep it missing.
The regenerative ability was linked to Naruto's hand seal, which disappeared when he sealed Kaguya. And... it was on the arm that blew off, so I don't think he can simply regrow it.