I'm not sure I entirely understand Jon's defense of Limbaugh. Or I guess I understand it; I'm just not sure why it's a defense. Jon says Limbaugh's point was just the flip side of the point he (correctly) made several years ago, which is that Democrats didn't need new ideas to regain political power. But, as Jon points out, Democratic ideas were already pretty popular. Republican ideas, by contrast, are deeply unpopular, at least once you get below the level of sloganeering.
Now, it's true that Democrats have benefited in the last two election cycles from more than just their popular ideas--they ran a good candidate, and the outgoing administration was imploding (as was the economy). But my read of the several election cycles before that is that Democrats were way underperforming relative to the their ideas, and Republicans were way overperforming relative to theirs. Now that reality has reasserted itself and the two parties are succeeding roughly in proportion to the strength of their ideas again, I think Republicans would be insane to stick with what they've got.
(I'd argue that the Bush implosion wasn't some random X-factor, it was what drew attention to the fact that Republican ideas are terrible, which is why Obama spent the campaign attacking Bush's worldview. Likewise for Obama's strength as a candidate. Obama wasn't a strong candidate simply because people liked him; he was a strong candidate because he was able to explain the fundamental attractiveness of the Democratic agenda. Or, at the very least, the way people felt about him personally didn't detract from the way they felt about the Democratic agenda, as it had for the previous two Democratic nominees.)