Well Gaga has already said she doesn't know if azealia will be on artpop but i think she'll definitely include britney if it's true britney recorded something for gaga
I'm sure that if Brit recorded something with Gaga she would put it on the album... but I really can't imagine that Britney would care enough to do this.
That song is currently titled Bottled Blonde and will be about Princess Di, Marilyn Monroe and other famous blondes who died before their time.
Bottle Blonde will have a vibe similar to Dance in the Dark, but more electronic pop - lighter feeling.
That video will be the conclusion to the Paparazzi/Telephone trilogy, with Britney co-starring with Gaga.
The tentative storyline for the video involves Gaga on the run from the police, getting help from Britney to change her appearance and identity. They begin to emulate the looks of famous blondes.