What can be predicted about the outcome of The Great Gatsby after reading the first four chapters?
Based on Nick's introduction to the story in Chapter I and the development of the characters so far, certain predictions would seem logical.
Daisy and Gatsby will meet again and resume their relationship. Gatsby has spent the last five years dreaming of this, and Daisy had missed Gatsby terribly when he left for the war. She had wanted to go to New York to see Gatsby before he went overseas. She got drunk before her wedding to Tom and cried, a letter from Gatsby in her hands. Also, Tom and Daisy's marriage has never been a strong and loving one; Tom's infidelities show this.
Tom won't take Daisy and Gatsby's relationship well. Tom is very arrogant and possessive. He is used to having his way. He won't give up Daisy easily. She is one of his possessions.
Gatsby's dreams will not turn out well. Whatever happens, based on what is known in the first four chapters, will be serious enough that it makes Nick go back home where he continues to think about Gatsby long after the summer of 1922. Gatsby will somehow be hurt or even destroyed by getting involved with Tom and Daisy. Nick says in Chapter I that something "preyed" on Gatsby and that "foul dust floated in the wake of his dreams."
Based on the story of Gatsby and Daisy, and what happened before she married Tom Buchanan, we might predict that Daisy won't ever actually leave Tom. Although Daisy was momentarily willing to back out of her wedding to wait for Gatsby, telling Jordan to give the pearls back and to tell the crowd that she'd changed her mind, after a bath and a little time to sober up, "the pearls were around her neck and the incident was over." The letter she'd evidently received from Gatsby made her second-guess her decision, and she held onto that letter until it disintegrated in the bath. Then, the next day, she married Tom "without so much as a shiver," and she left for her honeymoon as though nothing had happened. The memory of her love for Gatsby was enough to make her sad, but she ultimately decided to do the practical thing, the sensible thing, the thing everyone would expect her to do. We might surmise, then, that Gatsby's influence in Daisy's life might amount to little more than a crumpled reminder of the past, while she goes on to choose Tom again because he is the choice society would expect her to make.