I don't speak to my father because of his history of abusing my family and its contribution to my mental illness. I would be very sad if he died, and I can't fully anticipate how badly it might affect me, but I have spent a lot of my life grieving the person he was, could have been, and that I wanted him to be. I would understand completely why he would commit suicide. We share mental illnesses and the state of intellectual imprisonment. He cannot carry out his life's work because the stress exacerbates his mental illness so severely he loses touch with reality, and accordingly he is terribly isolated. His physical quality of life is poor and he has been homeless on and off for so long. His parents, in my opinion, screwed him over emotionally in a way that my brother and I inherited; when your parents desert you emotionally, you tend to spend your life pining for them. I don't think he will, though, and I am pleased that he is doing better these days. (It helps that he has a proper place to live now.)
I love my mother and would be devastated by her loss. I don't think I could cope at all. I would be shocked if she is suicidal due to the depth of the emotional conversations we have had, my insight into her psyche, and my previous attempts to find out why she isn't suicidal (when I was younger, I thought she must be lying to me that she wasn't suicidal, that everyone must be suicidal like me - especially because her suffering was so great, and because I had seen her pushed to the limits before and threatening suicide several times, which was traumatic). I think it would probably be deeply related to me and that is very difficult to process. I grew up enmeshed with her, so I am not normal - I did not start individuating properly on some emotional levels until my early 20s, and I have less capacity for coping with something like this than other people. But I don't think I would ever be 'the same' again.
She is my carer and in practical terms it would essentially invert my life. I am not sure I would have anywhere to live. While I could afford rent with a housemate and used to live on my own, all of that requires a lot of community support and physical assistance to make happen. I don't think my relatives would let me be homeless, but nobody is really in a position to support me themselves.
It depends on the children. Many children seem to recover with the proper support, but it's an enormous factor in suicide risk and even the ones that get through it come out with terrible scars; adults are better equipped to move on from the loss of a parent, and as they get older and see their parents aging and becoming sicker, they begin to accept it. Still, most of us live in countries where we can reasonably expect to have our parents around well into our own middle age unless they die of something like cancer. Also, suicide is perceived as a different type of loss to death due to aging, so that's something one would have to assess.