It's unclear whether this track will appear on Kanye or RiRi's upcoming album – iTunes lists Rihanna as the lead artist, though it's Kanye who was promoting the song earlier this week. UPDATE: Looks like Rihanna's claimed the song.
UPDATE #2: Kanye's close friend and barber of 19 years, Ibn Jasper, claims that McCartney is producing Kanye West's new album and that "FourFiveSeconds" is appearing on both Kanye and Rihanna's new LPs. It's unclear if McCartney is also producing Rihanna's highly anticipated eighth album.
On New Years Day, Kanye shared a single with Macca called "Only One."