Look into making the most of the time he has
Don't take this the wrong way, but consider either palliative care or hospice care
The easiest way to explain it is that his doctors goal up to this point may have been a number (having him achieve the highest age possible)
While palliative and hospice doctors say "forget at what age he dies, let's make sure he enjoys life till that day"
Probably the best decision we ever made for my mother in law is put her on hospice care