Hmm very very interesting chapter. I agree with Sogeking on the fact that Sabo is probably not dead. Also with the whole Sanji discussion, Oda put Sanji there for three reasons I think.
1. To get stronger of course. He will most likely learn some new kama techniques. I mean did you see the way those new kamas kicked?!
2. To meet Ivankov. Ivankov left appox. 2 weeks before the flashback started to go back to Kamabakka Kingdom. So I think that he might run into Sanji and that's how Sanji will probably leave.
3. Oda loves messing with Sanji. I mean come on, the wanted poster thing was too hilarious. Then the whole Duval situation. Seriously Oda continually messes with Sanji's character. I love it.