Looking purely from a business viewpoint, most businesses will be affected in some way or another. The act itself is only binding on Government, not business. This means that a business cannot and will not be prosecuted for failing to adhere to the act, as there are no requirements for adherence by business. The incentive for any company is the potential for more business.
Government itself must adhere to the act, which will have a cascading effect on the rest of the economy. If you do work for the government or want to do work, then you will need to become BEE compliant. One of the aspects of the BEE act is that in order to improve your BEE rating you should purchase from other companies that are BEE compliant. In this way since almost all businesses do work for other business, each business is going to require that their suppliers begin the process of becoming more compliant.
This applies to all businesses, large or small.
In summary, any business that does business with any other business would most likely need to consider their own BEE credentials.