Hmm, Justice Scalia just turned 78, Justice Kennedy will turn 78 later this year, Justice Breyer will be 76 in August, and Justice Ginsburg is 81.
The next few years will be crucial. They will probably set the direction of the court for the next 100 years. And I’m pretty sure that if Obambi is reelected, his next appointee will be a muslim.
I don’t know where you got those ages but Wikipedia lists DOB for Scalia as 3/11/36, making him 76, Kennedy as 7/23/36 which makes him 76 in a few months. Ginsburg’s DOB is 3/15/33 (beware the Ides of March) which means she is 79 and Breyer’s is 8/15/38 so he is 73 and will be 74 at the end of the summer.
Sometimes justices will step down when the president is a philosophical soulmate so he can replace them with somebody similar but it doesn’t happen all that much. I think it is very likely there will be no new justices during the next presidential term.