Dear sir i can understand your concern i am very sorry about her condition. in my opinion its very difficult to tell about the condition of patient without looking at her biological and electrolyte values. As you mentioned that her kidney is only 40% working and most probably she might be having infection on legs which is making blisters. By doing dialysis and effective treatment of infection we can improve the quality of life,by doing renal transplant its possible to make things to normal also. but with out dialysis and proper critical care management it may be difficult to pass the days. its very difficult to tell about life expectancy with out attending patient in detail Regards Dr vamsi krishna