The ones remaining in service have all been re-engined. However, they still have the same old airframe, many of them built well over 50 years ago.
They require a lot of maintenance to keep them flying. I suspect that has been cut to the bone, plus they have been run hard since 9/11/2001. It is a wonder we haven't lost more of these as well as other older aircraft. We have a rapidly aging and ridden hard fleet of military aircraft in all categories.
A responsible thing for an USAF General to do is ground all these aircraft until what caused this crash is known.
This might be over-reacting, but one saying is better safe than sorry.
But then the lives of US Service Personnel are cheap to Obama and company.
He apparently is more concerned with the issue of Gay professional athletes than the safety of US Personnel (Benghazi as an example).
Right now I’m 60/40 accident/manpad.