I agree ATNotts
Going seasonal would only go to shun the business travelers which are needed to make the service work. Business travelers need consistency and frequency if they are to shift their allegiance from one airline to another. if AA were to only operate on a seasonal basis, then why would business or regular travelers switch between the two? you would stick with the airline that operates all year round and collect the airmiles... not go from one to the other unless there is a major difference in product and service (which we know there isn't)
if AA want to complete with UA, then they need to bed in a compete on the long-haul (no pun intended)... so we just have to see if AA have the stamina... I hope they do!