Just 02 Stan Things
02 fan base: O M G but wHEN did the 02 Chosen disappear before Tri--- M E, AN INTELLECTUAL: It's under a year. Provided you are not one of the types of fans that believe "I can ignore everything Tri does and call that 'canon' regardless of what the franchise heads state since", In Bokura no Mirai, Takeru states it's 2005, and from the letter we can see it's DECEMBER, specifically close to X-mas. Since 02 ends at the end of 2002, that only gives a window of Jan 2003-Jun 2005. 2003 Spring is when one of the 02 Drama CDs happens, so that narrows the potential timeline to even further, Mar-May 2003 (regardless if Tri depicts the events or not - hell, we can assume the team of Jun and the others fell to Alphamon too!!!) If you pay attention to the timeline Koushiro literally gives us right at the beginning of "Saikai", we can assume the 02 Chosen Children disappeared right when everything "strange" began happening with the "Distortions" - which is implied some months before Tri. We can also assume (due to the fact they quite literally keep their 02 designs but more specifically their Digital World-only outfits) they were IN the Digital World (being affected by the Distortions) when it happened!!!