One thing to take into consideration is the possible comeback of Guilty Spark, the somewhat unpredictable yet amable monitor who we have learned may have once been a human very important to the Halo: forerunner saga story line. This is hinted at in the ending of Halo Primordium, where he takes over the [ONI?] ship upon which he was being interrogated and proclaims to the crew that he knows where the lifeshaper is, and takes off. I can only guess when in the timeline 343 was being interrogated, but it seems that it occurs sometime after the incident at Installation 04 and during a time when Humanities forces are not largely destroyed (because the ship was in a fleet when 343 took it over)