>>283098626
Battle harems are likely never going to become a mainstream trend again because every single trope and convention it introduced as a subgenre was absorbed by Isekaishit. There's always going to be a few odd ones made that are "pure" battle harem/battle school harem to satisfy the nostalgic otaku market, but as things stand Isekai has made it redundant. If you still want to read a Battle Harem series that has withstood these changes and is basically a living fossile, just read To Aru Majutsu no Index and its spinoffs. The main story is over 60 volumes long already.