Southwest Airlines is weighing changes to its cabin that could involve abandoning its single-class, open-seating system in order to drive up revenue, CEO Bob Jordan said told CNBC Thursday. The changes would mark a massive shift for the carrier that has stood apart from rivals for decades with its simpler business model."We're looking into new initiatives things like the way we seat and board our aircraft," Jordan said in an interview after the carrier's disappointing first-quarter report. Southwest's all-B ...