I'm not talking only about the '08 election.
...don't you think it is unreasonable to expect all conservatives to turn out...
I said "the Right," not conservatives. Conservatives tend to think they are the only people who occupy the Right side of the political spectrum, but they're wrong. I use the word "spectrum" for a reason. Just as on the Left, where the spectrum runs from comparatively centrist people like Sam Nunn and Leon Panetta all the way to the far Left Communists and other totalitarian types, the spectrum on the Right runs from barely Republican types like Snow and Dukakis, to true centrists like McCain, to conservatives, to populists of the Father Coughlin/Pat Buchanan variety, all the way to the far Right John Birch/David Duke types.
There's even a spectrum within the conservative part of the Right, and they don't always agree with one another.
A sizeable minority of the Right tends to have suicidal tendencies, politically speaking.
Proving that "true centrists" can't get elected.
Whomever the Republican party nominates in 2012 had best have a plan to recover the estimated 7.5 million voters on the Right who sat on their hands or voted third party. They're not going to replace them out of the moderate middle.