Per Writing a Novel, there are (at least) three ways to end a novel:
#1 The protagonist wins and consequently the antagonist loses
#2 The protagonist loses but becomes a better person
#3 The antagonist wins but, end the end, becomes a better person as well
Overall, the endings are positive, which is similar to Seth Godin's stance, but contradictory to Nabokov's, that there should be a(n) (altruistic) message in writing.
Seth Godin related that a writer's goal should be: "[...] marketing and idea spreading, working every day to deliver your message with authority [via writing]."