I think they may be leaving the old ramps in place, but new elevator cores and structural members have been going up for months now. The exterior will look nothing like the East side becasue of the elevators instead of escalators and by retaining the existing ramp structure.

The old upper deck was not physically attached to the Tiger Stadium lower bowl either. But the new deck will stand behind the bowl rather than overhanging it like the old deck, because the pitch was so steep that it bothered people.