Right now, she's the only artist with the potential to open with 1M+ in the US (Britney and Lil' Wayne might, too, but I think she has the bigger chances).
WW - definitely
US - It's not far-fetched, especially with the hype machine behind her. Kanye had similar hype in 2007 and he came very close (950k~). It depends on the longevity of BTW and Judas. But if I had to guess for now my range would be 500-700k.