Maelstrom_Divide said:
To me, it seemed strongly as if they died in the end.
If you look at the ending, Shinichi thinks he had let her fall. He clearly misses. He closes his eyes, and all of a sudden he's saved her (This is Point 1), with the help of Migi. Point 2, Migi is alive. He looks up and sees a serene sky. He tells her about the puppy, and somehow she knew, going as far as to assume she did. This contradicts her actions and thoughts earlier in the manga. Point 3, she is saying things that go out of character, but that seem to be exactly what Shinichi wants to hear. Point 4, the people on the roof believe that all of the bodies are dead and then, with a very slight smile on his face, Shinichi laughs, before a closeup of his right hand appears. His right-hand is perfectly stationary and shows no sign of Migi. Migi said it would be impossible for him to have any sort of consciousness for decades, so I find it hard to believe he would be able to will his way into existence for just a brief moment.
Everything goes exactly as Shinichi could have hoped, in every regard.
Then, the closing page. A shot of the planet with the text "I only want to feel some warmth... even from that which death would take from me."
I think it's an extremely ambiguous ending, in the same vein as Taxi Driver. It's up for debate whether the events in the last few pages actually happened, while being heavily implied to be just a fantasy within Shinichi's mind.
Migi stated that while he was inside Goto's body, he felt like a spectator, and because of that, almost invincible. Right before the dream scene where Migi tells Shinichi that he's going to disappear, there was some narrative that explains that some parasytes adapted to become like humans. Doesn't that say something about what Migi was trying to do? He's obviously changed and become less cold-hearted, and along with that I think he decided that being a spectator and helping out at times of danger would be the best thing for Shinichi, thus implying that his "decade slumber" is something he can snap out of at will considering he decided to do it himself. Also, I don't think that roof top battle panned out exactly like Shinichi wished... 2 people died, he got a knife stuck in his left arm, and he missed the grab with his right... definitely not ideal. It was Migi who helped.