Despite being slow off the blocks I feel some obligation to jump in, if only because I was primarily responsible for the Russia chapter in my book with Steve on ethnic irredentism - a chapter that features the Crimea case prominently. In that chapter we argued that Russia didn't go after the Crimea in the 1990s because, while the locals were supportive of such a move, there wasn't enough of a coherent Russian identity within Russia to fashion an ethnic irredentist campaign on.
That's still true today. Putin is no Zhirinovsky. But he is clearly running Russia as a strong man, meaning that he needs both carrots and sticks to maintain the power of his regime. And this brings us back to the argument of the Bill & Steve book - that irredentist foreign policy is driven no so much by primordial nationalism as by domestic political calculations. Just as Milosevic could be a Serbian nationalist (even if he didn't believe a lot of the primordialist rhetoric he was spewing), Putin can be a Russian nationalist if it helps his domestic political cause.
Here Kydd's piece (cited above) is onto something. The main thrust of his argument is international - is Putin trying to divide Ukraine or develop a bargaining chip to control them in the future? But there's a domestic political side to this, hinted at when Kydd writes:
It ["liberating" Russian-speaking provinces like Crimea from Ukraine] would certainly send a signal that crossing Moscow is very dangerous, and it would bring direct tangible benefits by bringing home Russian territory and populations while greatly weakening the rump Ukraine. Putin, the recoverer of lost territories! Putin as Bismarck!Irredentism is a signal not only for the future Ukrainian leadership, but for Russians at home. A lot of Western press focuses on the repressive side of Putin's regime - running politically-motivated show trials, jailing members of Pussy Riot, forcing critics into exile abroad. All of this is certainly real, but very few regimes can run on repression alone. Putin needs a base of support, preferably from a substantial majority of Russians who think he's doing a good job.
Whether "liberating" some bits of Ukraine will actually help build his base of support or not is an open question - but it seems reasonable to suspect that it will. It is certainly likely to play well in the western regions of Russia nearest Ukraine, where there are perceptions (however fallacious) of an impending Ukrainian "fascism" that will suppress the Russian-speaking population. If Putin can achieve either de facto or even de jure irredentism with a minimum of cost, the rest of Russia is unlikely to care much, generating a net positive for Putin's domestic political standing. The moment irredentism costs him serious political problems at home, I suspect he'll find a way to drop it.
Steve has wondered whether we will need to write a second edition of For Kin or Country to update the Russia chapter (assuming Columbia would actually publish such a thing). Certainly current events might warrant such an update, in that the previous outcome (no Russian irredentism) may be shifting before our eyes. But I think the underlying argument of the book is still sound. For all that Realists want to focus on the international balance of power calculations of the Russia-Ukraine relationship while ethnic Primordialists want to talk about the fundamental need for empire deep in the Russian psyche, in the end domestic politics tends to drive the bus. In that conclusion the book is still sound, even if the outcomes of particular cases change over time.