The Talmud relates that although the sanctifying of the new moon was to take place only in the land of Israel, R. Akiva would perform this action even in the diaspora, since there was no one on his level in the land of Israel. R. Herschel Schachter (Eretz HaTzvi, 32, fn 8) observes that this possibility shows that the requirement of being in the land of Israel is not a function of the land qua the land, such as is the case with the agricultural mitzvot, but rather a reflection of the nature of the land of Israel as the center of the Jewish people. Thus, the Sanhedrin is entrusted with this duty, not in their capacity as “Beit Din HaGadol”, but in their role as representatives of the collective will of the Jewish people. Accordingly, it is conceivable that in a situation where there is a genuine, recognized gadol hador, who is not in the land of Israel, he could be considered representative of the people, and establish the calendar.