The Prophetic Nature of Minhag

I have posted before on Rav Kook's concept of minhag. He holds that God endowed our national soul with a prophetic uniqueness. Its acceptance of practices is a type of prophecy. This national n'vuah-spirit is something that has real consequences. Here I simply want to quote a passage from the Talmud (מנחות לב:א) which supports this view:

"Rav holds that minhag prevails: If Eliyahu were to come and tell us that we may use a soft shoe for the chalitzah process, we would listen. If he were to tell us that we may not use a sandal [as is the custom and halachah today], we would not heed him."

Clearly, this passage tells us that in the future, when Eliyahu the prophet comes to clarify all confusing or complicated issues in Jewish law, he will not be contradicting any practices that have become universal to all Jews, and it seems that Rav Kook's concept of national n'vuah-spirit explains this.