I've never really understood all this talk about replacing Biden as VP. I don't see anything that would really cause that to happen, and I wonder why it's become so popular.
Biden is the oldest VP ever, I think, and look at what a mess the Republicans were in without the VP as a natural successor to the President. It's a beguiling thought and Biden seems like such a good sport about everything, while he has no ambitions to succeed Obama.
I think it's reasonable to speculate about this. I think it's too early to say if Gillibrand is the one, but she has to be considered a potentially strong candidate for 2016 as of now, the way George Allen was considered potentially strong for 2008 after his 2000 election.