Unless Bush can get one more Justice seated after Alito, the court will be split 5-4 in favor of the death cultists for another decade or more on all cases involving life or death issues. I don't think there are any viable Republican presidential contenders for 08 who would appoint pro-life Justices if they're elected. And if a Democrat wins, of course only people at least as liberal and pro-death as Ginsburg and Stevens will be appointed when openings come up.
If the Repubs lose 1 or 2 Senate seats in this year's election Bush may not be able to get a pro-life replacement confirmed even if Ginsburg or Stevens retire while he's still in office. IMHO, the outlook is pretty grim for the USSC ever having a majority of pro-life Justices anytime in the foreseeable future.
Yes, and the next justice most likely to retire after Ginsburg and Stevens is probably Scalia, and that's probably at least 15 years away.