I have no grandchildren; and as far as I know, there aren't any on the way in the immediate future. I'm doing with "the grandparent thing" what I did with the "becoming a parent thing", which is to consider all the issues I can think of, long before any child is actually on the way; and kind of try to sort out my own beliefs, philosophies, intended approaches/attitudes, etc. etc. My feeling has always been that if we prepare by giving enough thought to the issues we already know are going to come up, that makes a good foundation for dealing with the issues that arise and that we didn't know would arise. We deal with the worries and fears of being a parent when they happen, so I think we do something similar with grandchildren. In other words, we can't prepare for the unexpected worries and fears. We can just know that we've dealt with worries and fears before. Talking with future grandchildren's parents about how they view the role of grandparent is probably a wise start too.
So, to me, if you iron out the philosophies/approaches kind of thing and know you'll have to deal with worries and fears that come up as they do; then if you talk to future parents from the start (and keep having conversations "for the rest of time"), you've addressed a lot of the more basic, but sometimes, complicated things. From there, I'd think you might more easily be able to deal with the stuff you didn't know was coming (both good and bad), because you'd already gotten a lot of the other, more basic, issues out of the way before.
Personally, I'm not looking forward to having yet more people to worry about in this world; so one issue I'm working on now is keeping in mind that I have no control over which people get brought into this world by someone other than me, and I'm going to have to make peace with having more people to worry about in this world and in my life. I'll make peace with it, of course; but right now I'm preparing to work on reconciling my own preference that grandchildren not show up in the near future with the fact that I would, of course, be happy for any of my grown kids to have their own child/children.