Is Priyanka Chopra Ra.One's Chammak Challo?

This is what actress Priyanka Chopra and designer Manish Malhotra tweeted. That means that PC is going to be part of SRK-Kareena's Ra.One.
Usually MM works just for the songs, it means he's going to dress her for a song, so knowing the latest bollywood trend, it means that she is probably going to do an item song, and the only item song we know is in the movie is Akon's Chammak Challo! But wasn't Kareena going to be the Chammak Challo?
And if there are two item songs in the movie with the top two actresses of the industry...ladies and gentlemen get ready for the 3rd World War, the time is over for Munni and Sheila!