These aren't so much previews as test audiences/focus groups. Computer animation (CGI) requires a complex and time consuming rendering process. If they are still deciding on characters and actions, they would not be animated to their eventual quality, as it would be a huge waste of time and money. And I doubt, in my opinion, that there will be a "this attraction is in Tomorrowland because..." explanation. That would just call attention to the fact that it's a stretch. I think they'll leave it be, let the overall design say "futuristic-ish" and let it go at that. I mean they don't explain the Speedway or High School Musical either.