Spoiler:
In the original spoiler quoted by JP, it says that Anakin is wounded. I assume that maybe Obi-Wan cuts off Anakin's arm or both of them (even the mechanical one) Leaving him defenseless without the use of his lightsaber. Anakin sees that he has done bad, and his hatred for himself for what he has done is such a strong force, he kills himself by falling down into or near the lava. I think his legs will land in the lava and the rest of him will be porched on a rock. And this is how Palpy's minions find him. Of course the intense heat burns his skin and the fall prolly injures his head, knocking him unconscious, so the burning lava isnt affecting him on a conscious level. Hence the big gash on the back of his head in the OT.
Did anyone read that supposed spoiler about Anakin's dream from the novel over on TFN??. I dont buy it. There are too many quacks over there who "have some of the novel" or "know someone who worked at Lucasfilm".... I am not gonna post it bc I dont believe it, but if someone else wants to post it, go ahead...