Skynet's actions throughout the timeline causes a grandfather paradox, effectively changing all of history of the events leading to the future war, succeeding Skynet's goal in eliminating the Resistance established by Connor. However, it is heavily implied throughout the film that after the timeline's alteration, the party who saved Sarah has taken over the Resistance's place, having  their own time machine, and acts in anonymity to thwart Skynet's schemes and to prevent it from locating them.
Throughout the film's timeline, Skynet's actions create a grandfather paradox, altering all events leading up to the future war. This change allows Skynet to eliminate the Resistance established by Connor. Nevertheless, it is strongly implied that after the timeline has been altered, the party who saved Sarah now leads the Resistance, using their own time machine and operating in secret to stop Skynet's schemes and avoid being found.