This really is pure speculation. American are in no fit state financially to contemplate any transaction of this size. They are currently not regarded as a bankable credit in the aviation finance community. This means that for any new aircraft order, they would be forced to rely on significant financial support from the manufacturer or rely on operating lessors.
My own prediction for the future is that the largest order for the next generation of narrow bodied aircraft will come from one of the lessors, probably ILFC.
As regards the future of American, it is difficult to see them remaing in their current form. Their domestic market will in my view come under increasing pressure from carriers who are not burdened with the higher costs of the past. Their regional services will come under pressure from the lower cost operators and they will be forced to franchise these services more and more. Their best bet is probably to focus on developing quality long long haul where customers are still prepared to pay a premium for higher levels of service.
As regards the pilots input to the choice of aircraft, you are really living in the past. Airlines in this day and age will select the aircraft that make them the most money. The future trend is for increasingly more aircraft to be leased. Lessors buying large numbers of aircraft will go for commonality wherever possible and airlines will have less say in the final technical specification. This is because aircraft will be expected to fly for several airlines during the course of their operational lives, and nobody will be prepared to pick up significant reconfiguration costs. Involving airline pilots and engineers in defining the aircraft specification without commercial control in my experience often leads to over specificied aircraft whose residual values are compromised as a result.