An earlier assertion of multivalence in veRav Yaavod Tzair

On erev Shabbos, I spoke with Rabbi Nachman Levine, and besides pointing out to me other levels of multivalence in the prophecy of verav yaavod tzair, he noted that Radak preceded Ibn Caspi in asserting that the text was deliberately ambiguous. Radak's spin on it, just as Ibn Caspi suggested, is that at times Bnei Yisrael would prevail, and at times Edom would prevail. But he has an extra spin that the degree of certainly parallels the degree to which Edom would serve Yisrael. Radak writes:

ורב יעבוד צעיר, לא זכר עמהם מלה את שהיא מורה על הפעול. והנה הדבר מסופק ולא באר מי יעבוד את חבירו, הרב את הצעיד או הצעיר את הרב, אלא שיש בו מעט ביאור, כי ברוב הפועל הוא הראשון אלא בדברים שאין לספק בהם, כמו אבנים שחקו מים (איוב י״ד) מים תבעה אש (ישעיה ס״ד) ש
והיה זה שלא התבאר הענין בנבואת הזאת לפי שפעמים יעבוד רב את הצעיר, כמו שהית בימי דוד ופעמים יעבוד הצעיר את הרב כמו שהוא היום, ומעט הביאור שיש בנבואה זו, כי רוב הימים הרב יעבוד את הצעיר לפיכך היה הפועל ראשון, וכן יהיה אחר שוב שביתנו.

And the elder; shall serve; the younger -- it does not mention with them the word et which designates the object. And behold, the matter is ambiguous, and it does not explain who serves his fellow, the elder to the younger or the younger to the elder. However, there is a slight amount of resolution, because in most instances the actor is the first noun except among things which have no ambiguity, such as {Iyov 14}

יט אֲבָנִים, שָׁחֲקוּ מַיִם-- תִּשְׁטֹף-סְפִיחֶיהָ עֲפַר-אָרֶץ; וְתִקְוַת אֱנוֹשׁ הֶאֱבַדְתָּ.

19 The waters wear the stones; the overflowings thereof wash away the dust of the earth; {N} so Thou destroyest the hope of man.

and {Yeshaya 64}:

א כִּקְדֹחַ אֵשׁ הֲמָסִים, מַיִם תִּבְעֶה-אֵשׁ, לְהוֹדִיעַ שִׁמְךָ, לְצָרֶיךָ; מִפָּנֶיךָ, גּוֹיִם יִרְגָּזוּ.

1 As when fire kindleth the brush-wood, and the fire causeth the waters to boil; to make Thy name known to Thine adversaries, that the nations might tremble at Thy presence,

And this that the matter is not clarified in this prophecy is because at times the elder will serve the younger, such as was the case in the days of David, and at times the younger will serve the older, as it is today. And the bit of clarification that there is in this prophecy is because most of the days the older will serve the younger; therefore it is the first actor, and so shall it be after our captives return {in Messianic times}.

And so as noted, the ambiguity reflects the dual fulfillment in both directions; but he has this extra idea that that explanation which is strongly implied is also done so deliberately, because of the degree to which this interpretation will be true over the other.

I would add the following two points about multivalence here, and ambiguity as the message. First, of course a good reason to assume ambiguity and this switching off is Yitzchak's later blessing to Esav:

מ וְעַל-חַרְבְּךָ תִחְיֶה, וְאֶת-אָחִיךָ תַּעֲבֹד; וְהָיָה כַּאֲשֶׁר תָּרִיד, וּפָרַקְתָּ עֻלּוֹ מֵעַל צַוָּארֶךָ.

40 And by thy sword shalt thou live, and thou shalt serve thy brother; and it shall come to pass when thou shalt break loose, that thou shalt shake his yoke from off thy neck.

and his blessing to Yaakov:

כט יַעַבְדוּךָ עַמִּים, וישתחו (וְיִשְׁתַּחֲווּ) לְךָ לְאֻמִּים--הֱוֵה גְבִיר לְאַחֶיךָ, וְיִשְׁתַּחֲווּ לְךָ בְּנֵי אִמֶּךָ; אֹרְרֶיךָ אָרוּר, וּמְבָרְכֶיךָ בָּרוּךְ.

29 Let peoples serve thee, and nations bow down to thee. Be lord over thy brethren, and let thy mother's sons bow down to thee. Cursed be every one that curseth thee, and blessed be every one that blesseth thee.

But perhaps more than that. There was, after all, ambiguity and uncertainty on Rivkah's part, as to the meaning of the twins struggling:

כב וַיִּתְרֹצְצוּ הַבָּנִים, בְּקִרְבָּהּ, וַתֹּאמֶר אִם-כֵּן, לָמָּה זֶּה אָנֹכִי; וַתֵּלֶךְ, לִדְרֹשׁ אֶת-ה'.

22 And the children struggled together within her; and she said: 'If it be so, wherefore do I live?' And she went to inquire of the LORD.

The explanation from Hashem might not just be why they are struggling, but an explanation of the deep significance of the entire situation. And so they struggle together within her. Why the struggle? The answer is that sometimes one will prevail, and sometimes the other will prevail. And she is uncertain as to the meaning of their struggle, and perhaps who will succeed. So perhaps the meaning here is also encoded in her uncertainty. And so, it is left deliberately ambiguous who will prevail.