My $0.02:
One of the things I've noticed--and I'm sure many other fans have picked up on this, too--is that in Trek Lit, the stories of our heros, in theory, never end. One only needs to come up with a new good story to continue the action--continue with the characters' lives.
Which basically means that...in theory...one could follow the adventures of our characters until they eventually all die off.
Peter David touched on this point in a scene in The Captain's Daughter. Sulu explains to Chekov that, in theory, all stories would actually have sad endings, if you continue them long enough, to the end of the characters' lives. The trick, he continues, is to find a good high point (a last, great triumph)--and then end the tale, so it will be simultaneously happy and fulfilling.
So...how would you all think, for example, the TNG series would best end? Would it end with death...or retirement...or would it just go on and on, with all new characters, ad infinitum?