Rashi #1 and Rashbam: He meant that his vineyards would be so fruitful that a single vine will yield enough wine-producing grapes to fully load one Ayir, ¹ and one branch, a full donkey.

Rashi #2 (citing Targum Onkelos #1): Yaakov prophesied that Yisrael will return to Yerushalayim ² and build the Beis-ha'Mikdash, and that Mashi'ach will be surrounded by many Tzadikim whom he will teach Torah.

Rashbam: After harvesting the grapes and pressing them, his garments will be full of wine-stains. ³

Seforno: The nations having been destroyed by Hashem, one of the signs of Mashi'ach is the fact that he will be riding a mule (as he comes in peace), ⁴ another, that he will then tie it to a vine; the third sign is that he will then tie it to the thick branch; ⁵ and the fourth one, that he will be able to wash his clothes in the blood of his enemies. ⁶

Targum Yonasan: It refers to Mashi'ach girding his loins as he goes to war. He kills kings and rulers, none of whom can stand before him.

Ohr ha'Chayim #1: It refers to Mashi'ach. He will tie (incarcerate) the nations (who are compared to a donkey - "Asher Besar Chamorim Besaram" (Yechezkel 23:20)) in front of Yisrael (who are compared to a vine - "Gefen mi'Mitzrayim Tasi'a" (Tehilim 80:9)).

Ohr ha'Chayim #2: It refers to two famous redemptions - from Egypt, and in the future. ⁷ Regarding the first it says "Gefen," as in "Gefen mi'Mitzrayim Tasi'a" (Tehilim 80:9). Regarding the latter it says "Sorekah," i.e. at the time when "Eshrekah Lahem va'Akabtzem" (Zecharyah 10:8). There, it is plural regarding all aspects of the nations. At Yetzi'as Mitzrayim, Hashem humbled in front of Yisrael only Egypt and the seven Kena'ani nations, who are heads of all the nations, but all 70 nations were not given to be submissive to them. In the future, every nation will be given to them. It says "Asono," for also those who come from the female's strength (it is greater than the male's) will be tied in front of Yisrael.

Malbim: This hints to Mashi'ach, who will ride on "Chamor v'Al Ayir ben Asonos" (Zecharyah 9:9), and not on a horse, which is prepared for war. The [choice] branch represents the mighty nations.

Rashi #1: He meant that his vines would produce such an abundance of wine that they would be able to wash their clothes in wine.

Rashi #2 (citing Targum Onkelos): He added that they will wear wine-colored, regal-looking robes.

Rashi #3 (citing the Gemara in Kesuvos 111b): The wine will be of a high quality, that inebriates.

Targum Yonasan: He reddens the hills with the blood of the slain ones, and his clothes are stained with blood like someone who returns from the winepress.

Ohr ha'Chayim: The fourth [and final redemption] requires that Yisrael engage in the wine of Torah. Via 'laundering' in the wine of Torah, his garment (kingship) will be fit to wear.

Malbim: 'Levush' is a garment set aside for a specific matter. Kesus ¹ is anything that one covers himself with. The garment special for war, he will launder it in wine; Kesus (other garments) he will launder in Dam (juice of) grapes, which is less [esteemed] than wine.

Ha'amek Davar: Wine sharpens the intellect (Yoma 76b). Normally, a vine is thin; if one ties an animal to it, it will break. In Yehudah, they will be thick. Laundering is primarily with water, but a sharp liquid is good for stains. The custom in Yehudah was to launder with wine, due to its sharpness.

Rashi: Suso is an expression of enticement.

Ohr ha'Chayim: If there are not Bnei Torah at the time for redemption, ¹ it will come via harsh exile. If Yisrael lacks merit, Hashem will establish an evil king like Haman (Sanhedrin 97b) ... Dam Anavim hints to afflictions that purify Nefashos and clarify sparks of Kedushah, but they are not nice like Torah. The affliction will finish the preparation, like grapes are the ripened fruits of the vine. The nations will not spill so much blood of Yisrael, only isolated 'grapes,' but not a branch or cluster. "Suso" hints to a lower level than Kesus; it is an obligatory covering, an expression of Masveh. If the redemption will be via Torah and Mitzvos, the Supreme kingship will be revealed, and the vengeance of Yisrael [against their enemies, and Mashi'ach will appear] as an Oni riding on a donkey.

Malbim: This hints to Mashi'ach. Zecharyah 9:9 illustrates how the soldiers will be stricken. A metaphor for this is stomping grapes to extract their 'blood' (juice) - "u'Vegadecha k'Dorech b'Gas; Purah Darachti Levadi... v'Edrechem" (Yeshayah 63:2-3). "v'Ya'alu ha'Goyim...; Gas Heshiku ha'Yekavim" (Yoel 4:12-13). There are three levels in the stomping of Gog and Magog - (a) Harvesting the grapes; (b) Putting them in the winepress; (c) Stomping to extract the wine, i.e. Dam Chalalim. Yaakov saw grapes still on the vine, already stomped in the winepress, and the clothes became red from the blood. I.e., even when he comes on a donkey and ties it to the vines, his clothes were already laundered from the wine. I.e. it is as if the soldiers were stomped while attached to the vine.

Ha'amek Davar: Before grapes ripen, the liquid that comes from them is called "Dam Anavim." It is very sharp. "Sus" is a short form of 'Kesus,' i.e. a short garment that is not worn over the entire body, rather, only over the top, where one sweats more. Therefore, he launders it with Dam Anavim, to extract the sweat. Kelim 16:7 discusses Emum (a mold) on which they make Susos; they are shaped on a mold to cling to the body.