Definitely think you're right about the whole 3 train theme idea.
To expand on that, I've had the wild idea for a while that those characters will be included in a "Shed" element. With the transfer table being in front of the station, unlike Mystic Timbers, they have the opportunity to really enclose it and tell a story before the ride, instead of after. My guess is that they would use the 3 characters inside as well as use them in the 'Battle for CP' app.