This is fantastic. If he retires, even if the GOP wants to keep blocking SCOTUS noms for the entirety of Hillary's 1st term (don't lie, you know they'd at least think about it) there wouldn't be an even split anymore so the court could actually get stuff done even in the case of the GOP stonewalling everything.
And if they don't stonewall, then you're looking at 2 new liberal SCOTUS judges. Win-win.
And if they don't stonewall, then you're looking at 2 new liberal SCOTUS judges. Win-win.