Well, Naruto's friends and comrades from his past adventures are likely to be in it. But also, there could be some spiritual or mythical characters related to the concept of the golden fox. For example, there might be an old sage who knows the secrets of the golden fox and can guide Naruto on how to use its power properly. There could also be other villages' representatives who come to Konoha to see this 'Naruto with the golden fox' phenomenon and see if it poses a threat or an opportunity for their own villages.