HaLeivi,
someone showed me a sefer from the talmidei HaGra that Moshiach Ben Yosef is klal yisrael in eretz yisrael, and Moshiach Ben Yosef doesnt have to die, and 5751 (or 5750) is a pivotal time, taken from the first letters of amar oyeiv… in az yashir