Even if they don't face each other again, Al Nassr are winning more and more and have made a lot of progress, they have real chances to win the championship and I believe that this could be possible.
If even so, they don't win, Al Nassr's growth this season will certainly be a decisive criterion for them to be able to evolve and assemble a more prepared team for next season.
Like Al Nassr, I also believe that the entire Saudi Arabian league can still become one of the most competitive in the world.
I am not so sure where you are gathering your information, but as far as I know the winning streak of Al-Nassr is two games with a loss before that and the winning streak of Al-Ittihad is four games with a tie before that. If both keep going at the same average pace of the last five games, Al-Ittihad will win the title. That is what I read from the table.
I also read that in the Saudi Super Cup Al-Ittihad beat Al-Nassr 3-1 with Ronaldo playing the full distance. I further read that Al-Ittihad won 1-0 against Al-Nassr in the league with Ronaldo playing the full distance. There is just no indication (or perhaps I can't see it but everybody else can) that Al-Nassr is in a good position to win the title. It is of course still 8 games to go, but for now Al-Ittihad fully deserves the position they are in as they have beaten Al-Nassr in both games.