So I decided that my best hope was to go by car from Greenville to Atlanta, then get a plane to Miami. I made it to Atlanta and got through the 986,000,000,000,000,000,000-person security line and ran to the plane, which turned out, after we boarded it and sat for an hour or so , to have..... a maintenance issue! Apparently for optimal flying performance, both engines need to be working. So now we're back at the gate.
I may be spending Christmas at the Atlanta airport.