I'm not as optimistic as many of you guys about GANTZ.
Honestly, I think the mangaka is just pulling shit out of his ass and trying to find a way to end this manga (remember he said he wanted to finish it by the end of THIS YEAR!).
I think we're going to get a lot of plot holes by the time this manga ends, many questions will go on unanswered, or worst of all we could have one of "those" type endings.
You know, where nothing makes sense or where everything is conveniently tied up....I hate that shit, but I feel like it's going to happen with Gantz.