As much as I hate Wal-Mart....the Oxford site is being handled by a starchitect and located in the downtown core so I doubt that it would be your typical Wal-Mart. In the unlikely event that a Wal-Mart is even built here (which i really find hard to believe) there would be no possibility of a surface parking or a bland banal walmart warehouse structure.
Does Wal-Mart have any large urban stores at all that one could point to? At least I can easily think of a dozen downtown/urban Targets in the US, starting with the Minneapolis flagship. I certainly can see a large retail complex on Front, but to me, I don't see it as a prime location for Nordstrom or Simons, who I would think would prefer Yonge Street or Yorkville.