I don't really think a lot of Paul McCartney's fanbase would want to download a song with Rihanna/Kanye on it, so I don't think it's quite true that its 3 fanbases. More like 2 and a half.
It's a departure from what's on the radio right now, and it's her first new material in two years. Of course it will be selling.
thanks for being objective and saying it's different than stuff on the radio. i dont care if it flops but i will not have girls calling her hopping on radio trends. not this time