Chief is the single most main character of the entire Halo series, so if he were to die, it should be on the last (if there is a last) game: After the floods escape (somehow), Chief and the Arbiter evacuate the last planet with the Flood, staying behind....(sound familiar?). With no ride home, and thousands of Flood infested creatures approaching, Chief and Arby plant a nuke bomb in the last Gravemind, fighting off the Flood until they overwhelm them, Arby getting injured first, still fighting, then both of them ultimately killed by the Flood. Seconds later, the bomb detonates, destroying the whole planet with the Flood. No Spartans will be left alive (meaning Jameson Locke died earlier....At the hands of Jul M'Dama who flees the planet), but Earth is saved....Or is it?
End Cutscene: Lasky is staring at the window of the Infinity, telling Chief's life story. Once he's done, the surroundings fade to black, leaving only Lasky, then........BOOM!!!! A Flood infection form consumes Lasky, and the screen goes black
I changed my mind. This will be Halo 10 (If there is one)
#LongLiveArbiter!!!!