A win is definitely not happening; it's going to either Adele or Bowie.
Nomination? Maybe. It's early into the year but there's already a lot of competition, and I don't know if Rihanna can keep her momentum going until September.
Nomination...maybe. Keep in mind she was a no-show at this year's Grammys, and I'm sure some butthurt committee members will take that into consideration.