I say it will be Judge Diane Wood.
Why so?
I can't imagine President Obama nominating a male and, thereby, having only two women justices there.Convinced?
Judge Wood is from the University of Chicago--Obama's ol' stomping grounds
Her degrees are from the University of Texas, which breaks the Harvard-Yale stranglehold on the court.
Wood is a Protestant--Stevens is the only Protestant in the current court. (Six are Catholic, and two are Jewish)
Wood clerked for Justice Blackmun, who wrote the majority opinion in Roe v. Wade