American Airlines announced a firm order for 42 Boeing 787 aircraft on October 15th 2008, an order worth 8 billion USD's, with an additional 58 units on option. The 42 aircraft on order will be delivered between 2012 and 2018 and the additional aircraft would be delivered between 2015 and 2020. The Boeing 787 will have improved technological features over its older sibling, the 767, such as new composite materials including carbon fibers replacing aluminum, fuel efficiency with a 20% reduced fuel consumption, engine nacelles with "shark teeth" placed at the rear so that the noise emissions are lowered (this technology will also be applied to the all new Boeing 747-8) and passengers will feel less dehydrated on a long flight. The 787-9, the variant American initially chose, is designed to carry up to 290 passengers on a distance of over 6000MN. It will not directly replace the 767, although the 787 will replace the 767 in the long run, it will be used for expansion in the long haul fleet, and at a later stage when the 767 will be retired the 787 will take over the routes. But that's not yet for now, because the 767-300ER is still young.
The exclusive deal American had signed with Boeing for the purchase of only Boeing jetliners is void on paper, it means that American still is a privileged customer at Boeing but it is no longer restricted from going to other manufacturers.
The A330-200 is, in my opinion a great airplane, for its capacity, range and cost of operation. It has some advantages over the 767 including a better cargo capacity, but although it is not impossible I don't think American would choose the A330 or A350 over the 787. Phasing in the A330 into the fleet would mean increasing the costs of pilot training and MX and less flexibility in crew scheduling. I know this is very unlikely but American would still choose the B767-400ER over the A330, first for the reason I explain above and then it can be available sooner than a 787 or even an A330 or A350. The only reason I see American would order the B767-400ER is because it could be available much sooner than the 787 would be, or maybe additional 300ER's fitted with winglets and 777 style interiors so that a subtype is not added and that is even more economical (that's why American doesn't really want the 737-700), should it need additional aircraft for expansion sooner than previously planned. This will also depend on how the American economy will be doing in the next four years or so.
It looks like in the long run (2025 and beyond), the mainline fleet will consist of only these three types: B737-800 which will start showing its age, B777-200ER and B787, and maybe the 737RS if Boeing ever builds it.
