What could happen, instead, is a bigger-tent liberalism - somewhat chastened, perhaps, by some big-government failures in the Obama era - that makes libertarian intellectuals feel welcome, engages them in conversations about smarter regulations and more efficient tax policy, and generally woos them away from their culturally-dissonant alliance with people who attend megachurches and Sarah Palin rallies. This would make for a smarter left-of-center in the short run, but I think in the long run it would be pernicious. It would further the Democratic Party's transformation into a closed circle of brainy meritocrats, and push the Republican Party in a yet more anti-intellectual direction. And it would produce an elite consensus more impervious to structural critiques, and a right-wing populism more incapable of providing them. The Democratic Party would hold power more often, and become more sclerotic as a result; the GOP would take office less often, and behave more recklessly on those rare occasions when it did manage to seize the reins of state.
I see this as the time that the libertarian movement needs to make a very concerted push into the Republican Party, which is a much more natural home for it. Going to the left will keep it in the same second-class position it has occupied in the GOP as that party went on its religious kick, and, as Douthat points out, push the GOP even further into its unfortunately anti-intellectual corner. It would be a shame if things came to that.