In what way will your sun not come any more?
Radak: Also this is a metaphor; Targum Yonasan says, your kingship will not cease, and your honor will not be removed.
Malbim: Hashem's light, which will be for you in place of sunlight, will not set; it will be permanent - "l'Or Olam."
What is the meaning of "[vi'Yrechech] Lo Ye'asef"?
Rashi: This is like "Asfu Nagham" (Yo'el 2:10) - they gathered in their light.
Radak citing Targum Yonasan: Your honor will not be removed.
Malbim: Tzadikim and Nevi'im will not withhold their light.
What is the significance of "v'Shalmu Yemei Evlech"?
Malbim: Do not think that you will need to distance from the light and go to Galus again.