If Romney loses in November, the Republican base will no longer buy the electability argument for an establishment candidate. From the view of the base, the elites will have given away an eminently winnable election. Someone new, from outside of Washington, will be the party's nominee in 2016.
If Romney wins and does nothing to change the status quo, the economy will falter. He will end up as the second straight one-term president, and the nation will desperately be searching for an authentic outsider in 2016.
If he wins the White House, the only way for Romney to succeed will be to side with the nation's voters and throw out the club in Washington. That will be great news for the country but bad news for political insiders on both sides of the partisan aisle.