Delta has been perfoming surgery on their route structure and schedule for well over a year (such as eliminating their hub service it DFW), and this is likely to continue. Some articles that I've read suggest that Delta is likely to expand their international routes, further scale back some of their domestic service, and more-or-less leave Song alone.
The Chapter 11 filing gives Delta the opportunity to keep operating under court protection. Those of us with upcoming flights on Delta don't have much to worry about.