I think Saudi Arabia will qualify for World Cup using any possible way.
They spent a lot of money to buy Ronaldo and other European players, they also become the sponsor for Club World Cup, after everything they done for football, would they accept if they're not qualified for World Cup.
Lolz..will Ronaldo go and play as for them in order for them to qualify to the world cup. Ronaldo was signed to make the league popular and for people to recognize Saudi Arabia as a football loving country. Suadi have to play in order for them to qualify and if they can't, let them stay at home and watch of countries playing in the world cup so that, they can learn from their mistakes. No country will sell their qualification tocket to Saudi Arabia.
It doesn't make any sense for Ronaldo to play for Saudi Arabia. When Portugal is in the competition, Ronaldo will never leave his country team that he has been playing for, a team that is also considered one of the best teams so far as the World Cup is concerned.
This is the team that he has always worked so hard to push forward. Because of Ronaldo, I think this World Cup should be the last one he plays for Portugal before he retires.