Not sure how long i have left.

Last spring i was diagnosed with Pulmonary fibrosis. Initial google search said 2 years, next search a few days ago said 3 to 5 years.
I am scheduled to get another X-ray in December and then an appointment at Pulmonologist where i assume he will give me a more accurate prognosis.
Posting this here because i may need some advice etc. NOT looking for sympathy! May have some questions and seeking answers.
Background information.
December 22 I will turn 78 years old. My wife of 56 years died March 4 2016, her 75th birthday. We had 5 children and all are doing well. 4 girls and 1 boy. Have 8 grandchildren and 5 great children.
Other than my son being a republican everything is super with my heirs.
I believe all financial items are in line. Small amount of assets are all joint with children and set up for equal distribution to the 5 children. I have written a personal letter to each, sharing my thoughts and memories with them, will most likely add to these letters as time goes on.
I do have a 20 year old grandson living with me who is on the autism spectrum. A little over a year ago the court determined he cannot live with his parents and brothers. The environment creates havoc with his life. Since moving in with me he has calmed down and now spends weekends with his family. Frequently when he returns it takes a day or so to get him calmed down. He is a good person but has been raised to believe he is a loser and can do nothing. Sad story for sure, but I will do whatever i can to help him have a decent life. If only i knew how to get him a more positive attitude I would feel like success has been achieved.
He is a concern for me, not sure if i should make any special arrangements for him or just let him be another grieving grandchild.(He has told me he does not grieve for anyone and does not expect to ever do so. Hard ass? but i just fed the dog and had to sit in a chair for a few minutes to catch my breath, he asked me if I was alright.
Thinking about posting occasional updates on my thoughts, feelings and condition .
Nuff for now. If this post is not appropriate or not in the appropriate forum, removal will not offend me.