I don't have the specific date. But usually, there are teasers and previews that give hints about when the next issue is coming. Keep an eye on comic news sites and forums for updates.
One popular character is Damian Wayne. As Batman's son, he often plays a significant role in the next - generation stories. He brings his own unique skills and a complex personality, having been trained by the League of Assassins. Another is Terry McGinnis from 'Batman Beyond'. He represents a future version of Batman and has his own set of challenges and relationships. Also, Cassandra Cain, with her exceptional martial arts skills, can be a prominent figure in these fanfictions, perhaps taking on a mentoring role for the new heroes.
One interesting concept could be the evolution of Gotham City. In Batman Next Generation fanfiction, the city might have new technological advancements or social changes. For example, there could be new forms of crime-fighting technology inspired by Batman's legacy. Another concept could be the new generation of heroes and villains. Maybe there are proteges of the classic villains who bring a fresh take on evil, or new heroes who have different approaches to justice compared to Batman. Also, exploring the relationships between the old and new characters can be fascinating. How do the new heroes interact with the remaining members of Batman's old circle?