It's not set in stone yet, as the proposed design is yet to go before the city's Art Commission. Let's hope Apple has a better time of it than they did in Boston, where Boston's Back Bay Architectural Commission had trouble approving the Boylston Street store's design.
By contrast, The Art Commission's executive director, William Burke, seems enthused, telling Metro, "...[Apple is] going to clean all that off and purify the design. It's a nice building that contributes to the character of the street."
The store currently closest to Philly is the Ardmore Apple Store. Other than that, you've got to go out to Jersey.