Along the lines of the Shem MiShmuel's ideas about Eisav having two sides, that of complete evil that must be eradicated, but also a side of potential that may be used in a positive way, there is a fascinating medrash in Yalkut Shimoni, Beshalach 268:
Amalek asked Elifaz his father, "who will get olam hazeh and olam habah?" Elifaz answered that it'll be Benei Yisroel, and Amalek should build them wells and roads, and if he does this he will get into olam habah like the least amongst Benei Yisroel. But Amalek did not take his father's advice, and instead set out to destroy the entire world. Hashem saw this and responded to Amalek, 'Rasha, I created you as the last of the 70 nations, and now you will be the first of them to be destroyed and the head of those in gehenom.'
This medrash portrays that even the worst of Eisav's descendants - Amalek - has the potential to do positive for the Jewish people, and therefore merit a place in the world to come. However, he is not satisfied with this small piece (like Achav who was told that David would be greater than him in gan eden, so descided it wasn't worth it to do teshuvah). Instead, Amalek tries to destroy the whole world; which is a very childish attitude of, 'if I can't have it then nobody should.'
Yet there still exists positive potential in Eisav. In Ovadya 1:18, he says that in the future there will be no remnant to bais Eisav. The Gemara in Avodah Zarah 10b says that this only refers to those that do the actions of Eisav. If someone from the family of Eisav will listen to the angels in his life and choose to abandon the corupt ways of the family and join the Jewish people he can have a share in the times of Mashiach. We must try to be good role models and an ohr lagoyim, to help show them the way to redemption.