His part will play out just like everyone elses. It wouldn't make sense to just jump to his scene without clearing up other MAJOR things going on. He's nothing more then a mere battery for the white Zetsu's. Patience is the key here. Just like how you're wondering about Yamato; I'm wondering about Kabuto, and how long he's going to be trapped in Izanami. For now, he can be considered temporary "fodder".