Do you think Ruth Bader Ginsburg did the liberals a disservice by staying so long?

[MASHED POTATOES. VOTE!]

Yes, she should have retired in 2013 or 2014. She probably expected Hillary to win and underestimated partisan obstruction from Republicans for any Obama and later Clinton appointees. Imagine if things worked out the way they should have, we would be talking about 6-3 liberal court now (her successor, Merrick Garland and one more Clinton appointee for Kennedy).

Let's remember the reason for Obama picking Garland was that his age and moderate-ish credentials would make him easier to get confirmed by a GOP-controlled Senate. Of course we know how it turned out, but if he got confirmed, he'd be more likely end up with the swing bloc, rather than firm liberal bloc, at least on some issues. Also, we can't be certain on Kennedy retiring as he did, under a Democratic president.

In this case, we'd be talking about four solid liberal votes as before (Breyer, Sotomayor, Kagan and RBG's successor), but of course Garland, for all his moderate heroism, would still represent a swing to the left, replacing Scalia. But there wouldn't be a dramatic shift by RBG retiring.

[MASHED POTATOES. VOTE!]

I think it would be a better idea for President to nominate Supreme Court justices for a fixed 15-year term, without the possibility of reappointment, thus preserving justices' independence from political pressure, but also preventing somebody staying on for too long.

Right now, with a lifetime tenure, a nominee's age is the primary consideration: must be young enough to serve as long as possible. And, on the reverse, Garland's advanced (for a Supreme Court nominee) age was a factor that was intended to make the GOP more willing to confirm.  To be fair, RBG was already 60 when nominated, though it also should be noted that she wasn't first, not even second Clinton's choice. The process of finding White's replacement was pretty convoluted, with several candidates passing on (like Cuomo), or being passed over (like Breyer, due to the "nanny problem").