I think if she'd retired early enough in Obama's term, they'd have had to approve someone.  As with Robert Bork, it may not have been the first or even the second, but at some point the political winds would have turned back against him.

You do hit on an interesting point, though, and I see it here in Texas.  The hardcore conservatives seem to be MUCH more fixated on doing whatever is necessary to gain/keep control of the court.  The chatter about it is so pervasive on that side that I think it's coming from Evangelical religious leaders most of all.  That tells me Roe v. Wade is what's driving them - and probably their belief that the country receives a kind of collective punishment from their understanding of God for having it.  That's am almost unchangeable belief, but it's also a minority view in the country.  They might succeed in overturning RvW, but I'll predict that if they do, that's the exact moment they start to lose power and favor.  It would be a kind of slow act of self-immolation on their part - and for a group that already is losing power and % following each year anyway.