You seriously underestimate the principle of political cycles. Eventually, even without changing itself much, the GOP is bound to get power again. What they do, however, will greatly effect how quickly that happens.
It's easy to see political cycles, but hard to predict their partisan specifics. It is conceivable that should the Democrats succeed in winning over conservative interests that eventually take over the party, then Republicans could eventually pick up disgruntled liberals. It is also possible that the Republican Party could fade into insignificance and that the Democratic Party could splinter along a rift between conservatives and social democrats.
One theory (I refer to Neil Howe and the late William Strauss in
Generations and subsequent books) suggests that a eighty-year cycle that corresponds to the preservation of personal memories as the last people of political and cultural influence die off, go senile, or retire in their eighties. What people remember and despise they resist; for example, the financial recklessness and speculative boom of the 1920s offended people born as late as the mid-1920s. People who had no memory of an economic calamity often found the role of a George Babbitt (a shyster who sold people houses that they couldn't really afford) abominable. Such pro-business politicians as Barry Goldwater (born 1908) and Bob Dole (born 1922) had no use for such speculation, but once off the scene the shysters started to operate with impunity. People who remembered the economic meltdown of 1929-1933 and associated it with weak political leadership and rampant speculation that preceded it would resist any tendencies toward a corrupt speculative boom and would insist upon political process that would keep a Harding or Coolidge from becoming President of the United States. About 2000, those constraints vanished, we got Dubya (a very permissive leader toward shysters, rapacious executives, and well-heeled special interests who exploited religious intolerance). Could someone like Dubya have become President in 1980? Absolutely not. 1960? Likewise. 1940? More of the same. 1920? That's when we got Warren G. Harding, arguably the weakest President of the 20th Century.
Although the cause of political change between 2006 and now (and this will likely continue into 2010) was very different from that of 1930-1934 in cause (corruption as opposed to an economic meltdown, the economic meltdown coming later in recent months, and with no certainty that the 2007-20?? meltdown will last as long and maintain the severity) it suggests the end of tolerance for weak, inattentive politicians like Dubya who serve narrow clienteles. The Republican Party will either separate itself from the Dubya era and agenda or go the way of the Federalists and Whigs. We might be two years ahead of schedule for the economic meltdown parallel to that of 1929-1933 meltdown and things might not be as bad, but note well what happened in the 1930s and early 1940s: a worldwide depression, the rise of Satan Incarnate in Germany, two Japanese invasions of China, Stalin's forced collectivization and Great Purge, the Spanish Civil War, World War II, and the Holocaust. That is what Howe and Strauss call a Crisis Era, a time in which everything is at stake.
Nobody says that things this time will be as scary. Maybe this time we will have the historical knowledge (including film clips of dead bodies stacked like cordwood) that causes people to think twice about supporting leadership that makes its political points through street brawls. Kindness, caution, and conscience can thwart some political agendas, but they also can decide who ultimately wins any Great Struggle. But seventy-or-eighty years earlier some countries underwent wrenching change, violent rebellions and wars. That was the time of the Crimean war, the Sepoy Rebellion, the Taiping Rebellion in China, the Meiji Restoration (really a revolution), Canadian independence, the unification of Germany, Italy, and Romania, an abortive rebellion in Poland, French occupation of Mexico, the Franco-Prussian War and the Paris Commune, and of course the American Civil War.
After a Crisis Era comes a placid, conformist, and culturally-conservative time (a Recovery or High) when people are scared of major wars. Wars may happen as veritable appendices of major wars (the Korean War)... but all in all, people know their places and trust their institutions more. Optimism develops -- perhaps a little too much -- as the economic order rebounds. Then comes a cultural awakening in which youth who have no personal experience with the Crisis and its hardships challenge the fuddy-duddy grownups. The awakening peters out and adults clamp down on youth expression in an Unraveling Era while turning to corporate power and fundamentalist religion to solve all problems. At the end of the Unraveling everyone is a hustler because everyone knows that work pays badly but speculation and the right connections can pay off well, only to see those fail.
We are in a Crisis already; 2009 is roughly 1931 again. Barack Obama has many of the characteristics that one associates with Lincoln or FDR, which looks very promising until one remembers the times of those leaders. If we are lucky he will "only" be a composite of Theodore Roosevelt and Dwight Eisenhower... which is about as well as one can hope for a peacetime President. (Truman was a wartime President, and Jefferson was President when America was one of the few large countries at peace).
The Republican Party is in deep trouble, and one charismatic leader will not be enough to stem its decline. It has become a regional party for now supporting a coalition that represents about 40% of America, and that's before it stands to lose even more ground. It is not attracting the youth vote, which suggests that ten to twenty years from now the rising politicians who become city councilmen and state legislators will largely be Democrats.
It's possible to see how the Republicans of 2008 resemble the Democrats of 1980; twelve years after Reagan trounced Carter and a bunch of Democratic Senators lost their seats, Bill Clinton, a politician similar to Carter in ideology, won election in a near-landslide. But 2008 could be a portent of very bad times for the GOP. Should things go well enough, then Obama wins in a monster landslide in 2012 after the GOP loses even more House and Senate seats in 2010.
The period 1930-1950 was a bad time for the GOP; never mind that Truman barely won, he still won, and would have won in a landslide in 1948 had it not been for the Dixiecrat secession. The Republicans couldn't get people to forget Herbert Hoover until they had Dwight Eisenhower to offer. Eisenhower might have as well been a Democrat.
Say what you want about Herbert Hoover, arguably the greatest disappointment that America ever had as President until recently -- Dubya is worse.