Will diastolic blood pressure ever exceed systolic blood pressure?

No. Systolic blood pressure occurs during contraction of the heart. The blood pressure falls progressively until the next contraction. Diastolic blood pressure is the pressure immediately before the subsequent contraction. Diastolic blood pressure can never be higher than systolic blood pressure.
No. Pressure varies as the heart beats and relaxes. Systolic pressure is as high as it gets. Diastolic pressure is as low as it gets. The basement of a building can never be higher than the room.
Blood pressure. Diastolic pressure can't exceed systolic with normal physiology. If an eecp machine is squeezing in cardiac diastole, the intraarterial pressure could exceed systolic but this is a special artificial situation.