The drying process that the bones in the valley were experiencing was not going to change on its own.
The valley had filled with dry bones over time and God was ready to change the course for these bones. The valley that had long since represented death was about to become a strategic army base filled with an exceedingly great army filled of the breath of God.
A valley that is filled with dry bones is a valley that represents what used to be but is no longer. The valley that Ezekiel looked upon was a boneyard of memories and no longer a playground of possibilities. God, however, asked the prophet to imagine the impossible. Ezekiel was asked to envision these bones coming to life once again.