I recall having this conversation with Mark Miller several years ago.
Mark was genuinely upset that I could even conceive of a future where I
was not part of this team.  He was more upset when I pointed out that
human mortality guarantees an exit.  He then worried that I was
suicidal or terminally ill.  (I'm not)

It's not morbid, it's just practical.  Make every day count, because
you've only got so many days to see the sights.

In terms of team management, you can either ignore that fact of life
and set yourself up for disaster when the inevitable happens, or you
can build your team to survive departures and periodic change.

To assume that anyone will be working in the same office at the same
job 1000 years from now is absurd.

Over the past 20 years, the Borland development team responsible for
Turbo Pascal and Delphi has changed many times.  Some key people, such
as AndersH or ChuckJ, or Gary Whizin or Zack Urlocker, were very
visible (by their choice), whereas a lot more people equally critical
to the development team (such as Peter Sollich, the architect of the 32
bit Delphi compiler and my indirect mentor, and Eberhard Waiblinger, my
first manager at Borland and my mentor in software quality assurance
theory and application) were quite invisible, also by their choice.
The team has lost members by choice, by layoff, and by mortality.

Over the next 20 years, the Borland development team will continue to
change, adding people and losing people.  C'est la vie.

When you build your team right, change is not the end of the world.

-Danny