I don't have any information for you, but I do have a suggestion.
In the past when evaluating sites for a possible theater, I contacted various city managers' offices. One was able to tell me that there was a new 8-screen coming soon. Granted it was a much smaller city than Charleston, so they were more likely to be cooperative, but that it is one possible resource. Other places to check might be the city's economic development commission or the local chamber of commerce. All these organizations have an interest in getting the right balance of businesses in the community. Not only are they looking to recruit new businesses, but they will also tell you if they don't think it will work for whatever reason. They may not be cinema experts, but they are usually savvy business-people.
Hopefully someone will chime in here if they know something specific about the Charleston market.
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