Hmm... What if...
They took Sai's advice and didn't look for Rowen?
Rowen never woke up, so he and Ryo were both trapped in space.
Mia got pneumonia and died in the battle against Cale to get Kento out?
Ryo never got the White armor?
Talpa turned good?
In the last battle with Tapla, Anubis' advice was wrong and Ryo died.
Ulie was never born
Mia's grandfather really was evil and collected all the info on the armors for the Dynasty