It is possible because as Sanford's critique about the legislature went, there is a group of "appropriators" in the assembly, many of whom are former Democrats who are solidly anchored on the social issues and they might try to take her out. SC politics is rather rough and tumble.
The point is not that the other side is any less socially conservative tough. They are the Tea Partier/Club for Growthers after all and Haley is one of them to a large extent. It is just that the other side love their pork and use the social issues as cover. Think Nathan Deal versus Karen Handel in Georgia in the 2010 GOP runoff. Deal is a far right socially, former Democrat Porker, whereas Handel (though suspect on social issues is hardly a moderate by any means) was a fiscal conservative supported by Sarah Palin, just like Haley. Therefore I don't see Scott or DeMint challenging her.
This harkens back to an old divide that use to occur in Democratic primaries in the South when you had bourbon business and middle class types versus Progressive/Populist types and though both were racist, they would often use segregationism as a way to get a leg up on each other even though there real divide was on economic issues. The former were the first to move away from segregationist politics (though definately against busing) and the first to join the Republicans, at a time when their numbers were exploding thanks to suburbanization and the growth of the metros from northern transplants. The latter group, largely in rural areas shifted two or three decades later and largely on the issues of god, guns and gays of the 80's, 90's and 2000's. Nathan Deal switched in 1995. Rodney Alexander in Louisiana switched in 2004 largely to keep the pork flowing in. Therefore you have a war so to speak between the limited gov't types of like the Gingrich/Sanford variety against these former Democrats who began to rise to power in the Bush/Delay era.
A new dynamic has come into play dividing the business types between those who want the Gov't, corporate welfare, infrastructure, pork and a steady supply of illegal and legal cheap labor largely represented by the Chamber of Commerce up against the Club For Growth/Tea Party types who don't want the goverment interferring. What you are seeing is that the former is coming to ally with the more populist types and porkers and you see that occuring to some extent with Graham save for some McCainist tendencies on the pork and in Georgia with Kingston save maybe for the immigration issue.
