If they keep the characters and are able to somehow interpret the plots of 000 and such into that medieval style, then yeah, definitely! The characters and plot building as well as lore elements are what really make GBF, so making a lore out of medieval while maintaining those would make it work. Though at this point it sounds it'd be more like a Game of Thrones or medieval-esque TV show rather than a video/anime game and I uh... me and TV shows. Yeah lol (and movies too I don't really watch unless it's like the same favourite ones I always watch).