How Long Can A Person Live On Dialysis With 85% Kidney Failure

He has been on dialysis and goes 4 times a week for 5 years this past 3 weeks his kidneys have shut down completely and i worry because he is a bad diebetic and has lost a leg to the knee because of it.
Generally speaking the mortality rate for dialysis is about 15% for Peritoneal Dialysis patients, at 4 years, and about 25% for Hemodialysis our to 4 years.
What that means is that after 4 year, 85% of Peritoneal Dialysis patients are still alive, and 75% of hemodialysis patients are still alive.
Since the patient is going 3 times a week, this suggest that he is doing hemodialysis. Peritoneal dialysis is generally done daily.
Other figures I have heard say that about 50% of patients are still alive after 7 years.
All of this, though, also depends on the patients original state and other diseases, like diabetes. Being "bad diabetic" is not a good sign. Diabetes does HUGE amounts of damage to the kidneys, and is probably the reason they shut down. it is doubtful that they will start back up....
Dialysis is NOT perfect. It is MUCH better to have functioning kidneys! It is possible that the doctor might recommend increasing the treatments to 4-5 times a week.
The only other possible treatment is a kidney transplant, but being a "bad diabetic" would only ruin the new kidneys, and it is doubtful that the doctor would recommend this.