Restrict foreign workers result in drop of productivity?

I've read recent comments that certain individuals have been saying that the restriction of foreign workers result in a drop of productivity. The only reason this will be true is that the company has been relying on very cheap labour to sustain the business operations. Therefore, when you restrict the cheap labour, the business operations will collapse because the business model is no longer sustainable.

Looking at this issue from the perspective of a Singaporean, I would say that this will be a good thing for Singapore because if the business is relying on cheap labour to sustain business operations, that would mean that there is a depression of salaries for all workers in Singapore. However, we all know that inflation has been consistently high for a number of years. This cannot be sustained.

Business has to change in order to survive, and that may mean re-thinking the business model.