The only thing this Atlanta screening might've been the "first" of is a dcp made from the 2011 version, which in any event is still based off the 2004 Lowry master.
I agree that the RMW job was probably in preparation for the 3D conversion of the OT, which I would bet Disney is still gonna do.
It costs about $10 million to convert a two-hour movie to 3D. Each of the OT movies would at least do the same box office as TPM 3D, so I don't see Disney passing up that opportunity.