Every time conservatives sit back and just automatically ASSUME victory, we tend to lose (just ask John Thune in SD...and come to think of it, I predicted Tim Hutchisen would win merely because his state was pretty conservative).
While South Carolina tends to lean very conservative, the Senate seat you're talking about has been "safe Democrat" for 30+ years. The South Carolina Dems know that Fritz Hollings is a very strong incumbant and will therefore be doing anything they can to convience him to run again. If Fritz gets talked into it, logic dicates that it would be an huge uphill battle to unseat him. Bob Inglis was a great candidate, but check out what happened to him the last time around.
Now, assuming Fritz decides to retire instead of going for Thurmond's seniority, then (and only then) can we assume the odds are in our favor. Even so, the 'RATs will still have a silm chance of winning. When you look at what happened in NJ and MN in 2002, it's obvious that the 'RAT party will try just about anything to cling to power. They have a couple of popular statewide officials in SC, and I wouldn't be surprised if one of them were "recruited" to run.