Neo,
It wasn't metal fatigue but the two pieces where the plane breaks up in the video---they were fabricated too thin in the original production. That is what the excuse is. Other than that they want to push for the RAPTOR in larger numbers---i am pretty sure the USAF is going to get what it wants.
USAF pilots are very aggressive flyers---metal fatigue and strain is very abundant in the planes---just imagine if the plane has thrust vectoring---then calculate how much more stress is put on that air frame and the pilot. With the massive G forces faced due to thrust vectoring in the up coming aircrafts, metal fatigue is going to be the foremost issue alongwith the pilot "RED OUT" problems.
There is not going to be any repairs to that design fault due to high cost involved. That model of F 15 will be retired. The newer ones would fly till the raptor and other planes take its place.
USAF gets caught with its pants down---it is not possible. There is more to the story.
Neo, did you see the video.