Based on the renderings, it looks like there is still a "third" retailer (the brown two-storey storefront).
The floor plans and announced square footage still show Uniqlo taking the interior space to the west. I'm assuming Uniqlo really pushed for some street presence in negotiations... and successfully got a "hallway entrance" between Nordstrom and the "third" retailer (where the white facade goes down to street level). Looks like it also continues two-storeys above the yet-to-be-announced retail space.
The Uniqlo facade has not been built "exactly as in the rendering". The rendering shows a facade which is perpendicular to Yonge Street, and what has been built is at a 45° angle to it. I assume that was an early plan, mistakenly released now. Either the Uniqlo marketing people are geometry-challenged (more likely) of their render folk are truly clueless in this case.The Uniqlo façade is being built exactly as in the rendering. The Eaton Centre tower screens are not. They're continuing to follow the city documents of two vertical screens occupying the height of the tower. They're going to completely obliterate the Samsung screen which until now seemed humongous.