This. What an absolute waste if that is the case. I can't see how they will fit it in to the story otherwise, other than like I say, some sort of pre show with an actor along the lines of "We've had some strange reports in the station, people have been saying that an old floating Victorian train has been pulling up - I for one don't believe 'em me old cockney sparra knees up mother brown, oi oi, be lucky - and keep the secrets bruv!"
One would assume they will paint the whole building and over the "Rail depot" sign.
The building itself along with the train carriage, as previously said, has always been the most positive thing about the experience so if they manage to mess that up, that will be quite some achievement.
Anyway, we're getting a cafe so shut up and be grateful xoxo
EDIT: As an afterthought - would it be possible to just remove the hanging carriage in entirety as it's just a shell, so you step onto a tube train from the off? I guess it would? Again though - what a waste š°