Except your entire approach to the subject is flat-out wrong -- and I say this as a libertarian who hardly sees a difference in the major Parties.
Political science is empirical at least to a degree. History shows that, when one Party enters an extended period of decline, the other most emphatically does not "follow" - observe the lengthy twilight years of the Democratic Party between 1860 and 1884, or between 1896 and what is really 1932 - or, conversely, the state of the GOP for the twenty years between Roosevelt and Eisenhower. The "other Party" remains, simply waiting in the wings.
I agree with a lot of what you say. But the way you say it is absolutely asinine.
"Political science is empirical to a degree."
Quaint statement. Good political science/economics is
entirely empirical/theory-based.
Those periods that you mention are periods of dormancy, not collapse. The party out of power was still seen as viable. The main thing Democrats had going for them 2000-8 was overcoming weak Republican majorities. It was their marketing strategy. Twenty years before that split control of the executive and legislative branches was one of the means by which both parties stayed "viable" to the public. Republicans will no doubt employ the same marketing strategy in 2010/2. A positive feedback model best approximates the symbiotic behavior of the legacy parties. The corporatism intensifies with every "realignment" (realignments are becoming less accepted in political science), or with every successive administration.
"It's not what you said but how you said it!" How should I restate the corporate takeover of the country and global bankster thuggery via the legacy parties "competition"? Maybe I should look to Obama's Hallmark card grandiloquence. Oh, Smart Leader Obama! Show me thine ways of Chicago! I think it's an "asinine" attempt/argument to employ
ad hominen attacks by condescending someone's style when the arguments they are making are logically sound. Condescension comes easy to the Obama Fan Base.