If, as David Neiwert fears (with, alas, some justice), an Obama presidency were to be met with a wave of domestic terrorism -- as white supremacists, militia members and assorted other McVeigh-style right-wing crazies react to the election of someone who is not only a liberal, but an African American, with violence -- we will see mainstream conservative voices abandon -- all at once, with no coordination necessary -- everything they have said about terrorism in the past seven and a half years: that the proper response to terrorism is to destroy the culture out of which it emerges, that military force is the only proper response to acts of terrorism (and law enforcement approaches are too wimpy, etc.), that religions which are invoked to justify terrorist acts are ipso facto dangerous -- even, in some cases, abandoning the idea that no terrorist act is at all understandable, since some folks on the right will have sympathy for the future McVeigh's grievances if not their methods.
And no, this won't be met with any parallel switch. Liberals will believe what they do now: that terrorism is immoral and inexcusable; that it can be provoked by grievances both genuine and illegitimate, and that confronting those grievances (which does not mean giving into them or even acknowledging the slightest shred of validity to them) is essential to stopping future terrorism; that confronting the cultures that nurture hate is an essential part of ending terrorism*; and that the bombing and/or invasion of people who happen to share racial or religious identities with terrorists is not only an immoral response, but a flat-out idiotic and counterproductive one as well. And so forth.
(Actually, the one sort of "liberal" who will switch their positions were those who, in the run-up to the Iraq war, adopted the conservative position on the proper response to terrorism. Presumably the New Republic won't be deriding as pacifists those who oppose invading whatever state the future McVeigh hails from (or its uninvolved neighboring state that happens to share an ethnicity with the future McVeigh); even Tom Friedman won't advocate sending the U.S. army through such a state telling its residents to "suck on this". But really these pivots will be simply a subset of the above-mentioned conservative pivot: since anyone who supports invading random countries is not, in my book, a liberal in any reasonable sense of the word.**)
I can only think of one way in which this conservative pivot would not happen in response to such a right-wing terrorist attack: if they decided to ignore the fact that the perpetrator was a white, christian, right-wing, American extremist, and simply use the event as fuel for more calls to bomb people who are not white, muslim and non-American. Yeah, a few might do that. Because obviously if we don't bomb Iran in response to a domestic, homegrown terrorist's attack, we will never be safe. Which would, I suppose, be consistency of a sort.
Anyway, I obviously hope that the chatter from white supremacists and their ilk is just that -- chatter -- and that no such attack will happen in the event of an Obama presidency. If, however, the terrorist threat that Bush has decided to ignore*** does, in fact, occur in response to an Obama electoral victory, then the right-wing pivot described above is a virtual certainty. You can bank on that.
* And if you think that Bush and his cronies did any such "confronting", please see the clause following the above. Bombing or invading people who happen to share an ethnic, racial or religious identity with terrorists is not confronting anything, will make the problem worse, and in many cases is morally comparable to the original terrorist acts.
** This, alas, is a prescriptive rather than descriptive usage of the term. Many liberals do, in fact, have a disgraceful history of advocating -- and perpetuating -- invasions of random countries, to their (and our country's) eternal disgrace and sorrow; see, e.g., LBJ and Vietnam. But in the contemporary world, it seems to me that a distinguishing feature of liberalism -- that is, something that we should make damn well sure is a distinguishing feature of liberalism -- is an opposition to any and all aggressive wars that our political classes should take a fancy to.
*** Rather than react to by shredding constitutional rights and invading uninvolved countries.