It is a speculation but if you recall DAL was going to sell before the merger as DAL management felt it was burned by the Comair strike. There are couple of factors against Comair as far as DAL management is concerned and the foremost is that Comair is heavy with 50 seat RJs, which are no longer economically viable for DAL and Anderson needs to unload them and the quickest way to do that is to sell and it also raises cash. The other is there is a bad blood between DAL management team and Comair and more than a few aviation analysts have forecasted the sale of Comair as the likely scenario. But then again, who knows what the new DAL will do. They may just keep Comair and try to convert CRJ200s to all CRJ7 and 9s.