Dally is the most reckless, violent member of the Greaser gang, and he has an affinity for breaking the law, fighting rival gang members, and hanging out with his friends. Dally never explicitly mentions that he has a specific dream and is depicted as a relatively hopeless character with no future. After Johnny mentions that he is thinking about turning himself in, Dally expresses his love for Johnny and reveals that he lost his childhood innocence at a young age by going to jail. In jail, Dally became hardened and was never given the opportunity to regain his childhood innocence. After Johnny's tragic death, Dally loses his mind and purposely pulls out an unloaded weapon in front of the police. Dally wants to die after he loses the only person in the world he genuinely cares about.
If one were to surmise what Dally's dream would be, it would probably have to do with Johnny surviving his horrific injury. Since Dally loves the rodeo, one could also imagine that Dally might dream about riding broncos professionally. It is difficult to determine what Dally's dream would be because he is such a hardened individual, but the two things he certainly loves are rodeos and Johnny.