Removing foreign workers is the best thing that could happen to Saudi Arabia.
A country whose citizens do not work is in grave danger. Idleness breeds instability. If the foreign workers leave en masse, then their jobs MUST be taken by natives. This will create jobs for Saudi Arabians and give them something to do. In addition, they will get used to working for a living, which will be necessary in the long run, after the oil runs out. Al Qaeda is actually HELPING Arabia, although it does not know it.