the team going to the gantz ball should totally revive Sakuraoka, then the two kuronos, tae, reika, and sakuraoka can have an orgy while literally everyone else in the world is dead (including the alliens), and thats how gantz ends. this happens in the next chapter.
the scene is accompanied by a note by the author saying "hey, did you really expect something much better than this as the end? i mean, i just decided to forget about the entire vampire plot and just left if hanging with no real resolution cause i was bored with it, i do whatever i want, jokes on you"