What will be the relationship of all Jewish scholars to King Moshiach?
This question is an interesting one, because when Moshiach comes, all prophets and leaders of the Jewish People, past and present, will hear Torah directly from King Moshiach. All Jews, young and old, scholarly and simple, will learn Torah alike, just as the Jewish People learned Torah from Moses in the desert. If so, what will be the status of all other Jewish scholars, in comparison to Moshiach?
The Lubavitcher Rebbe explains that Moshiach will teach only the mystical dimension of Torah to the entire Jewish People. With regard to the Torah's revealed aspects, such as practical Jewish law, halachah, the scholars will not need to learn this from King Moshiach, as they themselves are experts in the field. As Rabbi Schneur Zalmen of Liadi, the author of Tanya, writes: "Moses and Joshua and the elders, and the scholars of all generations, who already know the revealed aspects of Torah, will not need to receive new laws from Moshiach." For questions in practical law, the scholars and sages will retain their stature.
Moreover, the scholars will still have an obligation to teach their students. The sages interpreted the positive commandment of a father to teach his son Torah as applying to a scholar and his students. No Jewish laws will be nullified when Moshiach comes; certainly, the scholars will fulfill the positive commandment to teach the people Torah.
Thus, the scholars and sages will continue to lead and teach the Jewish People. The only exception will be in the mystical dimensions of Torah, which Moshiach will teach to the entire nation equally.
(Likutei Torah, Parshat Tzav, 17:1. Shaar Haemunah, Ch. 56. Torat Menachem, 5746, Vol. 3, p. 138)