Meb ran his best time during his win in Boston in 2014 - just a few weeks shy of his 39th birthday.
Galen obviously still has the talent, the question is whether his back will cooperate. He has a disc issue in the lumbar spine. Doctors could operate but any surgeon will tell you that once you trim away disc material (which is irreplaceable), the odds that another surgery will be necessary in the future increases substantially. The alternative is to allow natural healing to take its course and recover/train through it - which is what Galen apparently has elected to do. Bottom line though, Galen at 80% is still better than our top American marathoners. We will find out in Orlando one year from now.