Radak: Bnei Galus should not despair from Ge'ulah due to what I said. Even though I will lengthen your Galus due to your sins and your fathers', I will not abandon you. I will take you out of Galus and return you to your land after your sin is paid.

Malbim: This concludes the Nevu'ah; it is primarily for the future. They sinned in Galus, therefore the Galus was lengthened. Hashem will punish the sinners, but the Tzadikim will remain and be saved.

Rashi citing Targum Yonasan: Like Noach was found innocent in Dor ha'Mabul. Tirosh refers to Noach; it is sweet. Eshkol is Dor ha'Mabul ¹ .

Rashi: We can explain simply (when wine is found in the cluster).

Radak: This is a metaphor. A cluster ripened its grapes to make wine from them. If one comes to destroy it, his colleague tells him "do not destroy it. There is Brachah in it." There is wine in it, which is Brachah and good. Even though it has grapes pits and peels, which have no Brachah, leave it due to the wine. So Yisrael - even though it has sinners, it has Tzadikim who are Brachah for the world. Due to the Tzadikim, it is improper to destroy it. Rather, just like they stomp a cluster to extract its wine, and discard the pits and peels, so Hashem will do to Yisrael. He will take them out of Galus when the time comes, and purify them on the road - "u'Varosi Mikem ha'Moredim veha'Posh'im Bi..." (Yechezkel 20:38).

Malbim: If a vine was totally ruined and produced bad grapes, if wine is found in one cluster that was not ruined, the vine's owner will say "do not destroy it. There is Brachah in it." So I will do, for the sake of Avadai, the Tzadikim; I will not destroy everything.

Rashi: They are every Tzadik found among [Yisrael].