Implied question: This is not truly Ako, for it is in Asher's portion, for it says "Asher did not dispossess the residents of Ako"!

Answer: Rather, it is the Techum next to Ako.

Question: In Bava Kama (81b), we say that in the division of Eretz Yisrael, every Yisrael received in the mountain, lowland, and dry land!

Answer #1: Some texts say [there] that every Shevet in Yisrael [received all of these];

However, here, the text says "there is no Yisrael [who will not have] in the world to come..." He learns from "Sha'ar Reuven Echad", i.e. to every one.

Answer #2: In this world, they do not have equally from this like from this, rather, a little from this and much from this. In the world to come, one has an equal amount of everything.

Implied question: It says "Sha'ar Levi Echad"!

Answer: It says also "Sha'ar Yosef Echad." Yosef is counted only like one Shevet (so with Levi there are 12).

Implied question: In Bereishis Rabah (Perek 2) it expounds from here that the Giv'onim will not be cured [from servitude], for it says "veha'Oved ha'Ir..."! (Here we say that this refers to the Nasi!)

Answer #1: Both are true. Since it used the word "Oved", we expound also Giv'onim.

Answer #2: Perhaps [the Midrash and our Sugya] argue.

Question: Granted, it is not considered a totally Stam Mishnah. However, this Stam should help to be like a Rabim, so R. Yochanan would be considered a Rabim arguing with a Rabim, and the Halachah could follow him!

Source: In Beitzah (2a), we say that regarding Shabbos, the Stam Tana is like R. Shimon, for the Mishnah says "we cut pumpkins [for animals and a Neveilah for dogs]...", even though it is a Stam followed by a Machlokes;

R. Yehudah argues with him, for it teaches "R. Yehudah says, if it was not a Neveilah from before Shabbos, it is forbidden";

Inference: [Even though it is not a totally Stam Mishnah,] it is considered like a Rabim against an individual! (The Gemara called it Stam to teach that we follow it, even though normally the Halachah follows R. Yehudah against R. Shimon.)

Answer: Perhaps it is worse when the argument is not taught immediately, for we can say that Rebbi retracted from the Stam, i.e. from teaching it anonymously.