Yeah, thats what I have read. Bungie offically says that Halo 3 will be the end of the Halo story arc, which I infer is the end of the story of John117. Being that there are still four other SPARTAN soldiers (Will, Fred, Linda, and Kelly), they could have several other spin-offs as well.
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For some extremely interesting reading, please check this out. It is a Wiki about the Ark in the Halo universe, which is belived to be the structure that the Covenant is looking for in the Halo 3 trailer. Please, oh please, read it
HERE.
Theories are:
- The Ark would be the point at which all of the Halo rings could be triggered, thus making Earth the Ark of which 343 Guilty Spark refers to in Halo: CE. Thus, the Ark would be the only safe place from the Flood, and the resulting explotions, tying the game to the story of Noah's Ark from the Bible.
- The Ark could be some sort of superweapon, used to destroy vast armies and planets. This would tie into the story of the Ark of the Covenant, how the Ark would contain something sacred of the Forerunners, possibly something to guarantee their survival.
The other theory with the Ark of the Covenant story is similar to that of what was told in Raiders of the Lost Ark, in which the Ark would be a large superweapon.
- Another theory to develop from the Ark storyline is one that again leads us back to Halo: CE. In the first game, 343 Guilty Spark refers to the Master Chief as a "reclaimer," someone who could operate the Halo rings. It was thought that only Forerunners could operate the Halo rings, but if it is also Humans who could as well, could the human race be decendants of the Forerunners themselves?