Where will Hashem go?
Rashi: I will depart from them, and return to Shamayim.
Radak: I will return My Shechinah to Shamayim, the place of My honor, for they belittled Me. My honor will not dwell among them. Malbim ? not only will I leave Efrayim to Yerushalayim ? I will return to My place and totally distance from Tziyon.
Until when is "Ad Asher Yeshemu"?
Rashi, Targum Yonasan: Until they consider themselves guilty, to admit to their sin.
Malbim: They will recognize their guilt by themselves, and seek Me to repent.
What is the meaning of "Yeshacharuneni"?
Rashi: They will seek Me. Radak ? this is like "Im Atah Teshacher El Kel" (Iyov 8:5). The first Nun is like the Nun in Yishme'un - sometimes it is added in future plural.
Malbim: If they will recognize their guilt by themselves, they will seek Me due to strong afflictions.