FR so far ordered 338 aircraft, 236 were delivered, around 200 in current operation. Even if FR will grow to 250 or even 300 aircraft fleet (which I doubt), they still have to dispose 200+ aircraft.
Absolutely correct to doubt that.
but most of the heavy maintainance is carried out at Prestwick.
FR don't do heavy checks: the aircraft are sold before a C check is needed. Keeps the costs down.