My first reaction to Delta to Eliminate Discount Carrier Song
was, “of course it failed.” It failed because they didn't burn their
bridges, didn't really commit, didn't do anything but a pale imitation
of Jet Blue.

But then I realized that Song wasn't a failure on at least one
level… it allowed a stodgy brown company to move fairly quickly and
to discover the power of story telling. Everything from the organic
food to the paint job was about telling passengers a different story.
Song had trouble keeping that promise, but at least they tried.

So maybe Delta learned a lesson about flexibility and speed and risk. Failure is rarely fatal.  [Seth's Blog]