Regarding the fate of Shinichi and Satomi, they hadn't sustained any mortal wounds, so it will be illogical that they died in the end. Also, in the Del-Rey edition, Shinichi mentioned when the people came and looked in their direction that they thought they had also died, which is also another proof that they had survived. I think that he and Satomi were just savoring the moment. Anyway, I was screaming in my head when Shinichi missed Satomi the first time that "NO, not her also. Isn't it enough that Shinichi had already lost his mother and Migi T_T"
It was sad seeing Migi go; he was my favorite character in the manga. Iwaaki mentioned in the interview in vol. 8 of the Del-Rey edition that he was contemplating drawing Migi's eyes in the close-up on Shinichi's hand in the end, but he decided not to. I would've loved if he had gone with that idea.
I wish if Del-Rey or any other company would license more of Iwaaki's work, especially the masterpiece, Historie.