This must have been tough to share, Sylvain.
Both of my grandfathers passed away years ago, and I felt similarly the way you did about your grandfather passing. They both had a long life and lived long enough to see their grandchildren having kids, which is I think what was really important for them.
But with my parents, I still feel that they're immortal, and I've no idea how to cope with the fact that they're not. But I hope they'll be around for a long time and I can share as much as possible with them in the coming years.