Hello, I'm a new community member, and here to ramble about some series predictions involving Nataku!
1. He's fulfilled his purpose in Saiyuki Gaiden, so chances are that he won't be waking up for another 500ish years. If he did wake up now, he wouldn't be willing to help Li Touten anymore, which would give Konzen, Tempou and Kenren a good factor on their side. However, they're going to die so it's unlikely that KM (Kazuya Minekura) will give them any good factors, and she's said that Gaiden's ending soon anyways, so it's unlikely that Nataku's going to move around soon.
2. If Nataku wasn't ever going to wake up, KM would've killed him outright instead of making him go comatose. However, if he wakes up on their way west, before the giant climax, it would make things too easy on the group. Another demon attacking? Who cares, they've got a War Prince!!! So, due to that, when Nataku does wake up, he's got to have more of a reason in the plot of the story than just to say "Hi, Goku!" or he would've been killed, meaning he's probably got to fight something only he can beat.
3. The Kogaiji group is working on ressurecting Gyumaoh, the giant demon who nearly killed Nataku the first time they fought. If he wasn't ressurected, it wouldn't be as dramatic, but no one in the Sanzo party honestly has a chance against him. Even with Goku, it's very unlikely. So what do they need? A war prince! So Nataku's got to wake up just in time to fight Gyumaoh. There's plenty of scary baddies to go around for the others.
4. The kid went comatose and had everything get screwed up for him once already, why should it happen twice? He just seems like the sort of character who gets a happy ending, but that'd require a happy Goku. So Goku, Sanzo, and Nataku have got to make it through the series alive. Hkkai or Gojyou can die, not both and maybe neither. The dead one has to die saving/helping the other.
And... That's about all I can think of to say on my Nataku-related predictions...