I'd rather GaGa saved the collaborations until later on in her career, she's already done more than enough!
Unless of course if Madonna comes a knocking, but really they should only collaborate if its going to be something truly epic and Madonna hasn't been epic for the best part of a decade!
I don't think she should do a song with Rihanna, I just can't see it working, I can't see their styles clicking, same with P!nk, Ke$ha and Katy Perry. She's been there and done it twice with Beyoncé, is there really any need to go another round with her.
I doubt after her comments that GaGa would work with Christina and I don't think Christina would want to go there.
I really don't think that GaGa has much respect or appreciation for Britney, I'm sure she shares the same views as her fans of Brit Brit. To GaGa, Britney represents all the things she despises in a popstar and a woman!
None of the male popstars are up to much these days so I don't think GaGa has any need for collaborations currently.