As a native of the Greenville MSA, I can say the it's certainly trending left. There are many northern and midwestern liberals moving to the city, and Grenville county was almost competitive in 2016. I also see potential but less likely shifts in Spartanburg and Anderson counties. Spartanburg did elect a pro-lgbt mayor, and Anderson elected a democratic mayor. They'll both take some work (Powdersville, the second most populous and fastest growing community in Anderson county, votes extremely conservative for example) but sometime in the future its possible. What should really scare republicans are the left-trends in Columbia, Charleston, and Greenville. The first two are already lost and Greenville, which they need in order to win, is due to flip soon.
Missouri, on the other hand, has been trending R since 2008. It seems like the trend isn't going away and the state won't be voting democrat for a long time. While a fluke is possible, statistically speaking SC is far more likely to be flipped than MO.
So white liberals (I'm assuming most of those liberal snowbirds moving from the northeast and Midwest are white) are turning South Carolina Atlas red?