The only way to get a prognosis is to take several blood and urine samples over time to determine how fast the kidneys are deteriorating. I'm in the process of doing that now with my Canidrome survivor. She's only 5 and in renal failure.
I feed half commercial kidney kibble and half homemade.
Homemade is a box of cooked pasta like elbows or similar amount of cooked rice. About 4-6 cups cooked veggies. And 4 baked chicken thighs. Or a dozen scrambled eggs.
CC gets half cup of homemade and half cup of kibble with a splash of water or broth twice a day. Her meds are amlodipene and benazapril.