To whom is "ve'eis asher Einenu Poh ... " referring?
Rashi, Seforno and Targum Yonasan: It refers to the future generations 1 until the end of time, 2 who are all included in the B'ris. 3
Shaabbos, 146a: It refers to the Geirim, who, although they were noit on Har Sinai, their Mazalos' were - in connection with the fact that, when T=Yisrael stood at Har Sinai (and declared 'Na'aseh Venishma'), the Zuhama (the filth) that the Nachash implanted into Chavah, 4 was removed from their bodies.
Seforno: Who need to be told that they only inherit the land on condition that they adhere to the B'ris. See also Torah Temimah, note 12.
See Sifsei Chachamim.
Targum Yonasan: And "... Yeshno Poh imanu Omeid ha'Yom" refers to all the generations from the time of the creation.
See Torah Temimah, note 14.