There will be a card based on the Catapult Turtle/Castle of Dark Illusions situation from the Atem/Player Killer of Darkness duel.After the card based on the Yugi/Ryota Kajiki duel, anything is possible these days.
If Shien and the Six Samurai are based on Oda Nobunaga's life, it's possible for the other Sengoku Basara figures to get cards of their own.
Red-Eyes Black Dragon is Alduin.Seriously, just look at them.
Evilswarm Kerykeion will infect another world.According to the fluff, Evilswarm Kerykeion is Constellar Rasalhague, who has used the Gishki Aquamirror to fuse itself with the thee corrupted Ice barrier Dragons. Ostensibly, she is not evil, in part due to Rasalhague being good in the first place. But she still contains the L-Swarm Virus in her, and as such may infect the next world that she and Constellar Sombres go to, now that the Duel Terminal world is gone.
Sophia has some relation with Noden, Nyarla and Cthugha.These three cards fulfill part of Sophia's summoning requirements, and Trapezehedron of Taboo can speed this process up.
Shien taught the second generation of Six Samurai Chronicbackstabbing DisorderAmong the legendary Six Samurai, Shi En is the only one that can destroy another Six Samurai to prevent his own destruction. Conversely, the original Six Samurai (their predecessors) all do, but their support monsters (who are aged-up versions of the Legendary ones) do not, except, again, for Shien.
Blackwing archetype is connected with the Mist Valley archetype.They got re-released in Tribal Force and they're Winged-Beast Synchro Archetypes.
Shrit/Necloth of Trishula will be the Shadoll's next victim.As Necloth of Trishula, Shrit is Level 9, the only Level not covered by the El Shadoll fusion monsters. Wen was the level 6 fusion monster because Wen means evil in the Ainu language.
The game would be a lot more popular if they could program a video game more like the animeSure you got your duel simulators, you got your weird early installments, you got odd sidebars. But if they ever got that kind of game right, a lot of those monsters would be house hold names beyond just nerdy card collectors. Hell imagine it as a war simulator even.