Hi and welcome to Healthcare magic.Thank you for the query.
I am sorry about his serious diagnosis. It is always hard to predict but without medical support this could happen in next 1-3 months. He will must be intubated sooner or later. This is very dangerous diagnosis, and respiratory obstruction usually develops slowly through several weeks. It wont be painful but it will be unpleasant in late phase when he will have conbstant choking
. I am sure you can find enough strength to go through all this.
Wish you good health. Regards