This is not a light topic, but if you are interested in exploring the idea, there has been tons of research done on generational world views (the elders, the boomers, Gen X, Net Gen, etc....) that looks at what has shaped their world views as they moved through the world. Most of the research is done in generalities of course, but I just finished reading about 'tribes' within these general generational models that describe some of the most common variants within them. It does not explain every individual of course. From a writing standpoint, if you are trying to explore how a Gen xer would react to certain changes in the future, do a bit of reading on that generation and how that generation (generally) sees the world. You could make some leaps in logic from there that would help flesh out a character, or groups of character. Don't forget to think about the cultural background of the character(s) as well since that may have more of an impact then generational issues.
Of course there are some things that happen to everyone as they get older - they get less impulsive (well, some of them) things start to ache, old wounds flare up, memory and vision issues, organ failures, etc - unless the world you create takes care of these issues, these would be common ground for 'old people' in all points in time.
Hope that gives you another perspective on the topic - it's just my two cents, for whatever that is worth....