This week, it was widely reported that Texas governor Rick Perry has been looking into the viability of a presidential run. Perry likely took note of the fact that the absence of Barbour and Huckabee means few Southerners are in the race: Few people associate Gingrich with the South, and Cain is considered a second- or third-tier candidate (so far).
It's true that there is a vacuum to be filled; Republicans are not satisfied with the existing field of candidates. Even before Huckabee and Trump dropped out, influential Republican leaders were already desperate enough to ask Christie to get into the race, despite his insistence that he won't run. The state of the race strongly resembles the "winning scenario" for Christie, which is why his probability of winning is so high.
But one point must be understood: Republicans aren't dissatisfied because there aren't enough Southerners in the field. There is no great demand for a candidate to fill the "Southerner" slot. Rather, Republicans want someone who can unify the Party, generate enthusiasm, claim to be a genuine conservative, and defeat Obama. They don't really care where the candidate is from.
This is why Barbour was not able to gain support for his own candidacy. He was Southern enough and conservative enough, but he could not unite the Party, display charisma, or demonstrate electability. Perry would face the same challenges, should he decide to run. Perry has denied any interest in running, but only in response to interviewer questions. As we've already seen, a denial is only definitive when it comes in the form of a self-initiated announcement or press release. Perry could run, but lack of voter interest is likely to deter him.