they'll probably be sucked into a black hole and ripped apart in ways we can only imagine
or burn up while being pulled into the gravity of another sun(provided they live that long)
or smashed by one of the countless of asteroids and objects out there
maybe they'll wander for eons through the great emptiness
what's even crazier still is that they may even survive us, they could be the first and last trace of humanity's existence before they're lost as well
but maybe juuusst maybe someone else will pick them up and put them away for safekeeping until such time we are able to bring them home
yeah, to think of what they will go through and what sorts of wonders they will see is something that is mind bogglingly sad.