The Jews trust in Hashem becomes so strong, that no one would go against Hashem ever.
Wow!
Amazing!
If they would have been able to lead the Jews to Eretz Yiroel
Moshe and Aharon would build the Beis Hamikdash. It would be the times of Moshiach.
The Jews trust in Hashem would not go up a higher level.
They would have then built the Beis Hamikdash, which would have been eternal, since Moshe built it.
Since their trust was not on a high level, they would sin. Hashem would have to take out his anger on the Jews, since the Beis Hamikdash was built by Moshe and therefore couldn't be destroyed.