Rashi: All that the Rasha toils and steals, he does not outlive his deeds. Everything [that he stole] will be taken from his children - "Banav Yeratzu Dalim" (Iyov 20:10).

Ibn Ezra #1: Everything under the sun is composed of the four 'elements' - fire, wind (air), water and land (earth), and returns to them. The verses here mention all four. It begins here with Eretz, for it is like one who gives birth. After it mentions the sun (5), the place of fire, due to its great heat, which 'fathers'. Everything formed from the land returns to it - "Ki Afar Atah v'El Afar Tashuv" (Bereishis 3:19), and the land endures.

Ibn Ezra #2: "Dor" is not a generation, rather, dwelling. This is like "mi'Dur b'Ahalei Resha" (Tehilim 84:11. I.e. residents on the land depart, and new ones come?)

Rashbam: Everyone dies and returns to the earth.

Ri Kara: All generations pass and are Batel. Just like the early generations passed, so will pass those after them. Therefore, I say that man is totally Hevel! However, the land is not Hevel, for it always exists.

Rid: This explains Havel Havalim - in the end man will die and leave over all [his acquisitions]!

R. Avigdor #1: Every day, 600,000 die and 600,000 are born. We know that a Dor is 600,000 from "Im Yir'eh Ish ba'Anashim ha'Eleh ha'Dor ha'Ra ha'Zeh" (Devarim 1:35).

R. Avigdor #2: Just like the generation goes and died blemished, so they come to Techiyas ha'Mesim. Do not say that it is a different and new world. Afterwards, Hashem will heal them - "Ani Amis va'Achayeh Machatzti va'Ani Erpa" (Devarim 32:39).

R. Avigdor #3: The generation that dies first, it comes to Techiyas ha'Mesim first, unlike the way of people. One who submerges thing in his furnace, the last that he puts in is the first that he takes out.

Metzudas David: Even if this generation will die in its place, another generation comes in place of it. Do not think to toil to acquire acquisitions to leave for your children (refer to 1:4:2:6).

Rav Sadya Gaon: It endures for its Olam (allotted time ¹ ).

Rashi: Who remains? The humble and lowly who lower themselves to the ground - "va'Anavim Yirshu Aretz" (Tehilim 37:11).

Rashi citing Midrash Tanchuma: All Tzadikim of Yisrael are called Eretz - "Ki Sihyu Atem Eretz Chefetz" (Mal'achi 3:12). R. Avigdor - we learn from "li'Kdoshim Asher ba'Aretz" (Tehilim 16:3).

Rashbam: The land does not move from its place.

Seforno: This refers to the cycle of renewal ² . Even though generations die, there is no change in the quality and quantity of the land [and what is found on it]. This is a wondrous Chachmah!

Metzudas David: Will the land remain forever?! Also it will wither like a garment and cease, with all its residents and all acquisitions!