Even if she does, she still has about $35 million from endorsements, $2 million from '4' royalties, and A Star Is Born all coming her way. I doubt she will get pregnant anyway since she is planning a tour and she has to shoot her future Academy Award winning role.
I think Rihanna will be on it this year. Since May 2010 she's sold millions of copies of LOUD and TTT, had a string of hits, her biggest tour to date, acted in a movie, released a fragrance and did a clothing range with Armani. If she doesn't make it now she never will.