Granny was pretty much the sole reason Ponyville stayed afloat during the war. She trained the youths and adults alike to survive. She was the biggest, strongest, and most robust elder pony in town. If you had a problem, you went to Granny for advice.
That big scar on her flank is where she actually had a hip replacement right before the draft. Had she not been recovering from surgery, she very well could have worked the farm and bucked trees herself.
I have not decided when or how she dies, because she is pretty damn old. But I do know she lives to see her other grandkids again.