Well, the Gangsta manga ends with a mix of closure and ambiguity. Some characters get the resolutions they deserve, but there are still elements that make you think and wonder about the future.
Maybe an orphan from a non - Uchiha clan who has a special ability that Madara finds interesting. This character would be malleable and eager to learn from Madara, as they have no other real family or guidance. They could bring a fresh perspective to Madara's teachings.
It could mean that there is a fan - created story (fanfic) about Naruto where the characters are depicted in a 'gangsta' - like style. For example, they might have the attitude, appearance, or behavior associated with gangsters in a modern or unique setting within the Naruto universe.
Probably not as popular as the more traditional Naruto fanfics. The Naruto series has a large following for its original ninja - based story, and the 'gangsta' theme might be a bit too far - fetched for some fans.