Will the sun not shine?
Rashi: You will not need its light.
Radak: Salvation and good are depicted as light. Your light will be so great, for it is Ohr Hashem, the great good, that the light of the sun and moon will have no significance at all. This is a metaphor, like "v'Or ha'Chamah Yihyeh Shiv'asayim k'Or Shiv'as ha'Yamim" (30:26).
Malbim: Until now, the sun shines by itself during the day, and at night, when it is under the horizon, its illuminates the moon, and the land receives from it. From now, it will not; it will be totally hidden and not found in existence.
How is Hashem glory for you?
Radak: You will be glorified in His honor and good that He will increase with you.
Malbim: This will be in place of receiving the sun's light via the moon at night. Hashem will designate His Elokus on you, the way the moon received the sun's light. I.e. Tzadikim and Nevi'im will be like the moon, absorbing Hashem's light at night (when His light is withheld from the commoners in the nation), and they will spread it to the nation.
