Justice Ginsburg was recently asked about retiring while Obama is still in office. Her answer was:
Who do you think President Obama could appoint at this very day, given the boundaries that we have? If I resign any time this year, he could not successfully appoint anyone I would like to see in the court. [The Senate Democrats] took off the filibuster for lower federal court appointments, but it remains for this court. So anybody who thinks that if I step down, Obama could appoint someone like me, they're misguided.