What is the meaning of "Nakel mi'Hyosecha Li Eved..."?
Rashi: It is a small gift in My eyes that you alone "will be My servant Lehakim Es Shivtei Yakov..."
Radak: Nakel is Nif'al (passive) Po'el Omed (the action applies only to the subject). It is said in astonishment; as if it says ha'Nakel; the prefix Hei is omitted. Why did you say that you toiled in vain? Is it a small matter to you that you are My servant?! Even if people of your generation do not heed you - is it not enough that you did My Shelichus?! Also, to stand up Shivtei Yakov from their fall in Galus among the nations - is it not enough that you prophesized about the good that I will do for them?!
Malbim: Do not worry that you did not attain the purpose for which you were created, and you did not complete the Avodah that I designated for you, to get Yisrael to repent. Now you are prepared for a greater purpose and Avodah than standing up Yakov (i.e. the 10 tribes) from their physical fall - they were exiled and scattered after Sancheriv's Galus. Hashem wanted (a) that Yeshayah will get them to repent, and return to their land and success, and (b) to return Yisrael to their spiritual success. Both of these were limited to Yisrael of that generation 1 . Refer to 49:6:3:3.
Malbim: Yeshayah thought that he toiled in vain; Hashem told him that his Nevu'ah will be fulfilled in the future. It will be a salvation of the Klal (the entire world) - "Ki Az Ehpoch El Amim Safah Berurah [Likro Kulam b'Shem Hashem Le'avdo Shechem Echad]" (Tzefanyah 3:9). Had it happened in Yeshayah's time, it would have been an individual salvation (of the 10 tribes from Chalach and Chavor).
What are "Netzurei [Yisrael]"?
Rashi: This is like "u'Netzuras Lev" (Mishlei 7:10). Their heart is surrounded with a Yetzer of thoughts of sin. This is "k'Ir Netzurah" (above, 1:8) - besiegers besieger it.
Radak: This is destroyed, like "uva'Netzurim Yalinu" (65:4). (You will return them to their former state.)
Why does it say "u'Nesaticha l'Or Goyim"?
Rashi: Additionally, I will make you a light for the nations, and to prophesize the fall of Bavel, which is Simchah for the entire world.
Radak: In the future, your Nevu'os will be a light for the Goyim. They will see that they were fulfilled, and they will repent to the good way. Through Yisrael's salvation, also they will be saved, after the war of Gog and Magog - "Yavo Chol Basar Lehishtachavos Lefanai", "v'Halchu Goyim l'Orech u'Melachim l'Nogah Zarchech" (66:23, 60:3).
Malbim: Now I anointed you to herald the great future consolations, for the general salvation in the end of days. This will be for the entire world. It will bring spiritual success for Goyim, to enlighten them to the true Emunah. It will be physical success via Hashem's salvation until the ends of the land. From when Sancheriv exiled the 10 tribes in Chizkiyah's sixth year, the time for redemption began, like I wrote above (refer to 11:1:1:1). Nevi'im started to prophesize their return. Had they repented fully, the ultimate redemption would have been in Chizkiyah's 15th year, when Ashur fell. This was possible as long as Chizkiyah lived.
