First of all, think about what your definitions of "war' and "peace" might
be. Whatever your response, the absence of war must surely be minimally
necessary for peace. I would argue that we should go further than that
to include all forms of strife, conflict, dispute, and other synonyms.
We are not currently at war with Iran, but I don't think we are at peace
with them either.
Some of you have described the book On the Beach was described as
"depressing", since we all die. And since your narratives about the end
of the Age of Stars parallel the book then I presume you could regard them
as equally depressing.
Suppose I argue the following
Peace is much preferable to war, with the term "war" taken to include strife,
conflict, etc., etc.
Human history is littered with wars, conquests, subjugation, enslavement,
etc., etc., and there is no credible reason to suppose that the future
will be any different. Even the animal kingdom has its territorial battles,
competition for mates, predator and prey, etc. Strife is all around us.
I could make the same argument about the cosmos, born of the Big Bang,
and containing stars which throughout out their lives are maintained by
the competition between hydrostatic pressure striving to expand them and
gravity striving to collapse them.. Gravity always wins in the end (once
fuel is exhausted), leading to the destruction of the star, only for new
stars to form from the remnants, and the battle to recommence. That is
Shute's narrative leads to a conclusion without strife, since there is
no one to strive. For the first time in the Earth's history there is true
peace, which is ultimately desirable (see the first bullet point).
and your narrative ends with cosmological peace for the first time since
the Big Bang.