To think DL wrote some game plan on repeling US is a little overblown. The facts, as they've come out in recent writings in the press seem to show otherwise. The more likely "story" is that had US entered their bid earlier, it would have been more likely to succeed. Also, in order to win, it seems DL has had to relegate itself to being merged as noted by the fact that the committee is requiring that DL emrge with no poison pill and a merger friend board. They seem to clearly see the advantages of Delta getting eaten up and are positioning things to go that way.
No buisness school in its right mind uses the airlines as case studies for much of anything other than bad business practices. They're not very profitable companies in the best of times, over-run by unions that drive poor decision making, short term thinking, testosterone driven organizations.
Also, it depends on what you consider success WT. To say there has never been a successful hostile takeover could be incorrect. Carl Icahn made a ton of money for Carl Icahn. I think everyone would agree that his main objective is to make money and he did. Was it to the detriment of the business? Sure, but that's rarely his focus. "Wall Street" is a pretty close interpretation of the fight between Icahn and Lorenzo and while the actual greed speech is attributed to Ivan Boesky (sp.?), Icahn is a dead believer in its content.