Okay, so before i explain my opinion, let me just say this, Code Geass is an anime, so the makers, Sunrise Enterprise, can decide whether or not Lelouch is actually still alive.
In my opinion lelouch is still alive. I doubt that with his intelligence and knowing how cunning he is, he could have died like that. The first time i watched this and it ended i was like "Wow that was such a good ending!" Then i rewatched it, and was like "The heck? Why did Nunnally read his memory?" A lot of people ask me that question and over time I've come up with a hypothesis.
First of all Nunally was able to see his memory because Lelouch obtained the Code from his father, Charles, when he killed him. In the first revolution (series) C.C. showed her memories to Lelouch when he touched her. Not only was he able to learn that if you have the Code you can show your memories to others, but he learned on other fact as well.
TO OBTAIN THE POWER OF THE CODE YOU MUST BE DEAD OR DYEING. And what exactly was Lelouch doing in the final episode? Dyeing.
Once you obtain the Code you are immortal and cannot die. Also if your one of those people who believe that the one in the wagon with C.C. is Lelouch, don't, cause it's not him. Knowing Lelouch, do you really think he would let anyone know that he was still alive? It would ruin the entire point of the Zero Requim. I bet that Lelouch is alive, and out there somewhere. Waiting for when he needs to return and bring back peace to the lands.
