Nothing happens in Saudi Arabia unless the King wills it.
In this case, he had to see the numbers of foreigners in the country as a long-term and short-term problem. I wouldn’t worry. You now have 50,000 less people to do manual labor in the kingdom. Who exactly do you think is going to do all the crappy work? Saudis? Never in a thousand years. You can’t even get a Saudi to change tires on a car, or fill the radiator up with water.
The Saudis are getting afraid of their foreigners. Lots of them are Shia. Since the foreigners do most of the work, if they got together, they could do a Saudi spring, and Iran may be planning that.
If so, immigration reform in this country could cause the same effect no?