If Obama loses his base, who will be loyal to him? The increasingly discredited neo-liberals, blue dog Democrats, and liberal internationalists (Clintonian foreign policy experts like Richard Holbrooke)? The black community? Those folks do not a viable and electable coalition make, without the progressive/liberal community.
And how do you win back disillusioned progressives and unionists? Possibly by changing direction in a believable way. But that will take not just words and speeches but concrete actions. And so far, those have been far and few between.
In this environment (admittedly this is looking way down the road), a moderate Republican like Pawlenty or, Gawd forbid, another Bush called Jeb, could make a very strong showing in 2012. Or, to think the unthinkable, another Clinton named Hillary could pose a primary challenge and split the Democratic party. (Think Jimmy Carter and Ted Kennedy in 1980, or Gerald Ford and Ronald Reagan in 1976, or George H.W. Bush and Ross Perot in 1992.)
All of which is very depressing.