The entire two last two short paragraphs are as follows:
Gatsby believed in the green light, the orgastic future that year by year recedes before us. It eluded us then, but that’s no matter—tomorrow we will run faster, stretch out our arms farther . . . And one fine morning——
So we beat on, boats against the current, borne back ceaselessly into the past.
In the penultimate (second-to-last) paragraph, Fitzgerald uses both an ellipsis and a dash to trail off and then break off at the end of two consecutive sentences. This shows that the American dream—"the green light, the orgastic future"—has not died with Gatsby. It will continue on with the rest of us, at least for those of us, like Gatsby, who have a dream stirring in our hearts. We cannot choose to not run after the dream. We will always stretch our arms to try to grasp it. And then one day ("one fine morning"), it will seem as if we have grasped it. However, the ellipsis and the dash indicate that while people will always continue to chase the dream, it will always be just a hairsbreadth out of reach.
Nick, however, never gives up the idea that one fine morning we can achieve our dream, though he knows this is impossible, because, as happened with Daisy and Gatsby, the dream captured is the dream at least slightly tarnished. Yes, the dream is always centered on the future, but, as the last line of the novel notes, it is also paradoxically rooted in the past. In other words, we are always trying to right or recapture what happened in some ideal real or imagined past moment. The early settlers of the American continent were trying to correct all the wrongs of Europe to recapture Eden—just as Gatsby was trying to reorient time so that he and Daisy would not be separated. The dream is both an attempt to determine the future and an attempt to recapture the past. It may be doomed, but it is still pursued.