Here is a good example how one network level strategy (strategic alliance) has changed to another (M&A). The point of interest in this story is the fact that it is not a deliberate strategic option by Lufthansa but an emergent strategy.
BMI being taken over by Lufthansa
UK airline BMI is being taken over by Germany's Lufthansa.
Lufthansa is buying the 50% of firm owned by BMI chairman Sir Michael Bishop, who forced the purchase under a long-standing agreement.
Read the whole article at: http://news.bbc.co.uk/1/hi/business/7697261.stm