As Nick has noted "that as many as four justices may be on their way out during the next four years," I thought it appropriate to repeat this paragraph from a decade-old (to the date) profile of Justice Souter in The New York Times Magazine:
The widely anticipated retirement of John Paul Stevens after the Court's 1994-95 term is expected to result in his replacement with a similarly mainstream voice [as then-new Justice Stephen Breyer], and only an unanticipated departure from the more conservative ranks of O'Connor, Kennedy, Rehnquist, Scalia and Thomas is likely to generate any significant ideological shift in the Court's alignment. If none of those justices leave prior to the 1996 Presidential election, the eventual timing of William Rehnquist's departure as Chief Justice -- generally expected to occur after, rather than before, the 1996 balloting -- looms as the next turning point in the Court's history. Whoever replaces Rehnquist as Chief Justice -- and whoever as President gets to make that choice -- will be responsible for piloting the Court into the next century.David J. Garrow, Justice Souter Emerges, N.Y. Times Magazine, Sept. 25, 1994, at 36.
Just a little perspective.