Similar to putting all our eggs into one basket with the F-22, investing the future fleet in two brand new aircraft is also a little risky. Not only are these new aircraft, but a new generation of aircraft. Any bugs in initial deployment could be disastrous. Also, it would be a real pain if the stealth capability gets defeated by a new aircraft detection system. It would be like investing in a top of the line battleship in the 1930s and then everyone else buying an aircraft carrier to sink it. Although, the chances of this happening are not high enough to stop investing in new technology and cancel the orders.