The swing guy has all of the power on a court with Clinton-appointed frozen-in-time 60s-era Leftist judicial activists on it. Nice summary by Betsy.
Apparently the joys of a sunny, golf-filled Florida retirement are not yet beckoning Justice Stevens or "Sleepy" Ginsberg. Power is difficult to give up, and to pass on to younger folks. It is getting to be a pattern where these Justices want to die in the saddle. Plus it's an easy job for the Justices: their associates do all the lifting, and the perks and vacation time (June to October) can't be beat. A pretty good gig, except for the lousy government pay. Senile dementia is no problem, because you have tenure and only God can fire you!