What good did Moshe promise Yisro now, that he did not promise him in Pasuk 29?
Rashi: Although the Torah does not explain what the good was, they later gave Doshnah (the fertile land) of Yericho - five hundred Amos by five hundred Amos 1 - to Yisro's descendents 2 - to Yonadav ben Rechav 3 (for five hundred years - Oznayim la'Torah) up to the time that he Beis-Hamikdash would be built. 4
Ramban (on Pasuk 29): This time, 5 Moshe promised him an inheritance in Eretz Cana'an in return for assisting them in the conquest of Cana'an. 6
See Ba'al ha'Turim.
Rashi: As the Pasuk states in Shoftim, 1:16).
Even though he is not mentioned there, but in other places in Tanach - See for example, Yirmiyah, 35:1.
At which point it was given to the owner, whose land had been appropriated to build the Beis-Hamikdash on it.
Refer to 10:30:1:2*.
Ramban: Which they later received, even to the point of being obligated to bring Bikurim from it and reading the Parshah.
Did Yisro remain with Yisrael, or not?
Rashi: Refer to Sh'mos, 18:13:2:1.
Ramban: Yisro remained with Yisrael and entered the Land together with them. 1
Seforno: Yisro's sons did indeed remain with Yisrael. 2
Ramban: As stated in the Yerushalmi Bikurim 1:4. Refer to 10:32:1:1**.
Seforno: As the Pasuk testifies in Shoftim, 1:16. See also Oznayim la'Torah DH 'Vehayah ki Seilech Itanu' #1 & #2.
