According to this USAToday.com [2] article, "Capacity, debt and fuel prices are the three biggest issues facing airlines, according to world-renowned aviation analyst and consultant Darryl Jenkins. How airlines manage these challenges will shape the future of air travel and impact how we fly over the next five to 10 years. The issues are likely to impact airfares, schedules, bankruptcies, consolidation, fleet composition, airports hubs and much more."
Links:
[1] http://www.library.northwestern.edu/libraries-collections/evanston-campus/transportation-library
[2] http://www.usatoday.com/travel/columnist/grossman/2010-04-06-capacity-debt-fuel-prices_N.htm