I think the lesson to be learned from this is to both the GOP establishment and conservatives — they need each other to win.
It needs to start with the GOP returning to the party of fiscal conservatism. But also, conservatives need to understand the limits to their power. They can choose when a Republican loses, as they did here and with John McCain, but they cannot win entirely on their own.
The idea the conservatives caused John McCain to lose is a complete fallacy that can not be backed up with a single fact. John McCain didn't need anyone's help to lose.