Murray is 5000 points behind Nole. He is not as consistent as Djokovic. Some miracle would need to happen for Murray to become #1, don't think it's gonna happen, 0.00001%.
How is that a problem? If Murray and Nole would meet in the AO semifinal, and Murray would win and win the competition afterwards, the difference would shrink by 2560 points. After that, Djokovic has 1360 points to defend in IW-Miami, Murray only 610. With a good clay performance (I said it before that this would be the key), Murray can pull ahead. Remains to be seen, but 5000 points is not THAT much.