Here's my thought like many others before me. Since this is a teaser, it is not canonical. Basically it is showing us that Master Chief will receive new armor, that the jetpack will return, and that the planet his ship is falling into is not a planet after all. Think back to Halo 3, when they released the video of the Chief throwing a "shield grenade" and then running into a crowd of brutes on earth in a desert, was this in the game? No it wasn't, it's just a fictional teaser, not a factual story. Also the rumor about HCEA containing a possible key for the eventual Halo 4 multiplayer beta is starting to make more sense now that Halo 4 was announced. But who else thinks they need to change the name. Halo 4 sounds kinda hackneyed.