Ive been NC with my mother for nearly a year now. She's in her 70s. So possibly she could die soon. Though of course she could drag on for 20+ years.
My brother is also NC with her. My dad died a while ago but had divorced her prior to this.
There's no way I can get back in touch with her. She's poison. Makes up nasty shit. Tries to get between me and dd, between me and Dh. Says stuff to to dd and then denies it and accuses dd of being a pathological liar, etc. I get the occasional nasty, lengthy letter from her which just rants about how ashamed I should be of myself.....not entirely sure what for. 
I'm glad I'm not in touch with her, the last year has been the best of my life. But I worry about whether I will have any regrets when she dies. She has no family and my step mother who sees her weekly at church says she doesn't have any friends either. I don't like to think of any elderly person been lonely but then I keep telling myself it's her fault!