Greetings my fellow Zombies fans and theorists, newcomer approaching! So, I made this account because I was reading the discussions about Brock and Gary in the 40s and Shangri-La's date, and thought that there are some things being overlooked. I also thought it would be fun to finally contribute to the work being done here, so now I'm writing this text. Onto my thoughts...
Firstly, I am positive that Shangri-La as we play it is set in the same year as Moon. Consider the following: The crew can only time travel by combining their means of teleportation with the Wunderwaffe DG-2; the crew teleported to Shangri-La at the end of the Call Of The Dead Easter Egg; as they're teleporting, Richtofen leaves behind the DG-2 as a gift to the CotD crew. This means that they cannot travel through time anymore from Shangri-La onwards, as they don't have the DG-2 anymore; if they can't time travel, Shangri-La and Moon need to have their dates very close to each other.
Secondly, Brock and Gary being dead in the 40s in the new timeline, even though they were alive by the 2000s in the old one. While Mystery Machine theorizes that they were born earlier in this timeline, I think that they finally managed to catch a break and survived the events of Time Travel Will Tell (Shangri-La's EE) instead. Assuming they still activated the temple's time travel system (and also remembering that it was in the past that they originally died), they'd still be stuck in the past if they survived. Now that they're alive, they can show the world that they found the location of Agartha, become famous and... Well, die in a plane crash weeks later, sadly.
If we also assume that the 'past' they travel to is the 40s (which everyone around here seems to agree that it is), everything fits with the cypher in Zetsubou No Shima.
So, what do you guys think? Makes enough sense, doesn't it?