Likutei Sichos – Vol 23 p 172 ff – Goyim in Liasid Lavo

Balak

The idea that there will be no Goyim Liasid Lavo (as understood from the Even Ezra, A Possuk in Zecharia and Raish Lakish), is completely rejected here, on two grounds: 1) There is a need for Goyim and much indication in Torah and Halacha, that they’ll be there 2) The Torah (and Hashem) are kind and not in the business of destroying entire groups of people. This Sicha therefore explains that the question is whether Goyim will serve their own purpose or exist only as secondary to the purpose of Jews. There are two opinions and according to the RamBaM and the Alter Rebbe they will have their own purpose then (also).