Brad DeLong makes a probably good point about the future of the filibuster:
[T]he filibuster as we currently know it is going to fall--it almost fell under Cheney, and only the fact that a few Democratic senators decided that it was worth "preserving" and so knuckled under to Republican policy priorities with which they did not substantively agree has kept it in being.Why only probably good? I agree with DeLong that the current Republican party will not hesitate to eliminate the filibuster should they have the chance and the incentive to do so. And I agree that a party that really wants to change the rules of the Senate with 51 votes can almost certainly do that, so a future Republican majority will have that chance.
The Democratic Party has a choice: it can either break the filibuster when it has the majority, or it can let Republicans stall and then let them break the filibuster when they have the majority.
The question is, however, whether that future Republican majority will have the incentive to do it. As Matt Yglesias notes, the only time it really makes sense to take the hits that would come with changing the Senate rules in that type of maneuver would be in times of unified, not divided, government. Yglesias predicts...well, that's too strong...he thinks its plausible that Republicans could have control of the House, the Senate, and the presidency in 2017. Could be! But he's not quite precise enough. It's unlikely, I think, that a Republican majority would accept the downside of filibuster-busting if they had only 50, 51, or 52 Senators. First of all, it would be harder to muster the votes to do it. But second, the reward would be so much less, because the GOP would want to maintain good relations with marginal Democratic Senators, which would be hard to do while enacting the "nuclear option." On the other side, if Republicans had 60 or more Senators, eliminating the filibuster would also be less rewarding, because they wouldn't need it.
So: we need a world in which the Republicans hold the White House, the House, and something like 53 to 59 Senators. Moreover, they need to get those victories while remaining similar to the current Republican party. If they get to 53 by adding five more Olympia Snowe types, well, that's not going to push them to eliminating the filibuster. Of course, that doesn't seem likely at the moment (right now, I'd guess, just from general press reports, that the incoming class of Republicans next year will be more conservative and less inclined to honor institutional norms than the current group of Republicans). But parties can change, and should they wind up with only modest gains in 2010 and a severe setback in 2012, it's certainly possible that Republicans could move to the center at that point.
I'm not saying that it's impossible at all for the conditions to be right for Republicans to repeal the filibuster as soon as 2013. In fact, it's possible (but I think highly unlikely) that Republicans will win the Senate in 2010, and immediately eliminate the filibuster in anticipation of a GOP sweep in 2012. But it's at least equally possible that Republicans will not regain unified control of government for some time, and that the Republican party that does take control looks less unified and ideologically rigid than today's minority Republican party. It's probably worth noting as well that the longer they stay in the minority (and assuming for the sake of this argument that Democrats leave the filibuster alone), the more vocal Republican Senators and Republican candidates for the Senate will be about the many virtues of the 60 vote Senate. Could they turn on a dime should they win? Yes, they could, but it's another cost pushing them to avoid at least an immediate confrontation over the rules (which hurts the chances for any change, because the least illegitimate way to change the rules with 51 votes, everyone seems to agree, would be to do it at the beginning of a Congress). And of course, if they don't act in the first Congress in which they have a good incentive to act, then there's always the possibility that they wouldn't get another chance for a while.
All told, I'm not sure which way I would bet on the chances of the Republicans eliminating or sharply curtailing the filibuster over the next decade. Ah, I'll go ahead: if pressed, close call, but I'd bet against it happening by spring, 2020. Not saying it won't happen -- and I totally agree that the current Republican party would not hesitate if they believed it was in their interest to do so -- but it's really not quite as much of a sure thing as one might think.