Actually, given how they really upped the detail on the maps and buildings to facilitate the little wonder movies... I'm surprised they don't just zoom into the map, using the leader's actual capital as background.
Given the camera work they already had to do for the wonder movies, this feels like a logical extension. Maybe with a shader/filter on top of it to match the lighting of the leader.
I highly doubt any of the in-game models other than wonders are high-poly or high-res enough to bear that kind of close up.